HTML5: Edition for Web Authors

This document is a strict subset of the full HTML5 specification that omits user-agent (UA) implementation details. It is targeted toward Web authors and others who are not UA implementors and who want a view of the HTML specification that focuses more precisely on details relevant to using the HTML language to create Web documents and Web applications. Because this document does not provide implementation conformance criteria, UA implementors should not rely on it, but should instead refer to the full HTML5 specification.

This document is an automated redaction of the full HTML5 specification. As such, the two documents are supposed to agree on normative matters concerning Web authors. However, if the documents disagree, this is a bug in the redaction process and the unredacted full HTML specification takes precedence. Readers are encouraged to report such discrepancies as bugs in the bug tracking system of the HTML Working Group.

Status of This document

This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the most recently formally published revision of this technical report can be found in the W3C technical reports index at http://www.w3.org/TR/.

If you wish to make comments regarding this document in a manner that is tracked by the W3C, please submit them via using our public bug database. If you do not have an account then you can enter feedback using this form:

If you cannot do this then you can also e-mail feedback to public-html-comments@w3.org (subscribe, archives), and arrangements will be made to transpose the comments to our public bug database. Alternatively, you can e-mail feedback to whatwg@whatwg.org (subscribe, archives). The editor guarantees that all substantive feedback sent to this list will receive a reply. However, such feedback is not considered formal feedback for the W3C process. All feedback is welcome.

Implementors should be aware that this specification is not stable. Implementors who are not taking part in the discussions are likely to find the specification changing out from under them in incompatible ways. Vendors interested in implementing this specification before it eventually reaches the Candidate Recommendation stage should join the aforementioned mailing lists and take part in the discussions.

The publication of this document by the W3C as a W3C Working Draft does not imply that all of the participants in the W3C HTML working group endorse the contents of the specification. Indeed, for any section of the specification, one can usually find many members of the working group or of the W3C as a whole who object strongly to the current text, the existence of the section at all, or the idea that the working group should even spend time discussing the concept of that section.

The latest stable version of the editor's draft of this specification is always available on the W3C CVS server and in the WHATWG Subversion repository. The latest editor's working copy (which may contain unfinished text in the process of being prepared) contains the latest draft text of this specification (amongst others). For more details, please see the WHATWG FAQ.

There are various ways to follow the change history for the HTML specifications:

The W3C HTML Working Group is the W3C working group responsible for this specification's progress along the W3C Recommendation track. This specification is the 10 January 2012 Editor's Draft.

Work on this specification is also done at the WHATWG. The W3C HTML working group actively pursues convergence with the WHATWG, as required by the W3C HTML working group charter.

1 Introduction

1.1 Background

The World Wide Web's markup language has always been HTML. HTML was primarily designed as a language for semantically describing scientific documents, although its general design and adaptations over the years have enabled it to be used to describe a number of other types of documents.

The main area that has not been adequately addressed by HTML is a vague subject referred to as Web Applications. This specification attempts to rectify this, while at the same time updating the HTML specifications to address issues raised in the past few years.

1.2 Audience

This specification is intended for authors of documents and scripts that use the features defined in this specification.

This document is probably not suited to readers who do not already have at least a passing familiarity with Web technologies, as in places it sacrifices clarity for precision, and brevity for completeness. More approachable tutorials and authoring guides can provide a gentler introduction to the topic.

In particular, familiarity with the basics of DOM Core and DOM Events is necessary for a complete understanding of some of the more technical parts of this specification. An understanding of Web IDL, HTTP, XML, Unicode, character encodings, JavaScript, and CSS will also be helpful in places but is not essential.

1.3 Scope

This specification is limited to providing a semantic-level markup language and associated semantic-level scripting APIs for authoring accessible pages on the Web ranging from static documents to dynamic applications.

The scope of this specification does not include providing mechanisms for media-specific customization of presentation (although default rendering rules for Web browsers are included at the end of this specification, and several mechanisms for hooking into CSS are provided as part of the language).

The scope of this specification is not to describe an entire operating system. In particular, hardware configuration software, image manipulation tools, and applications that users would be expected to use with high-end workstations on a daily basis are out of scope. In terms of applications, this specification is targeted specifically at applications that would be expected to be used by users on an occasional basis, or regularly but from disparate locations, with low CPU requirements. For instance online purchasing systems, searching systems, games (especially multiplayer online games), public telephone books or address books, communications software (e-mail clients, instant messaging clients, discussion software), document editing software, etc.

1.4 History

For its first five years (1990-1995), HTML went through a number of revisions and experienced a number of extensions, primarily hosted first at CERN, and then at the IETF.

With the creation of the W3C, HTML's development changed venue again. A first abortive attempt at extending HTML in 1995 known as HTML 3.0 then made way to a more pragmatic approach known as HTML 3.2, which was completed in 1997. HTML4 quickly followed later that same year.

The following year, the W3C membership decided to stop evolving HTML and instead begin work on an XML-based equivalent, called XHTML. This effort started with a reformulation of HTML4 in XML, known as XHTML 1.0, which added no new features except the new serialization, and which was completed in 2000. After XHTML 1.0, the W3C's focus turned to making it easier for other working groups to extend XHTML, under the banner of XHTML Modularization. In parallel with this, the W3C also worked on a new language that was not compatible with the earlier HTML and XHTML languages, calling it XHTML2.

Around the time that HTML's evolution was stopped in 1998, parts of the API for HTML developed by browser vendors were specified and published under the name DOM Level 1 (in 1998) and DOM Level 2 Core and DOM Level 2 HTML (starting in 2000 and culminating in 2003). These efforts then petered out, with some DOM Level 3 specifications published in 2004 but the working group being closed before all the Level 3 drafts were completed.

In 2003, the publication of XForms, a technology which was positioned as the next generation of Web forms, sparked a renewed interest in evolving HTML itself, rather than finding replacements for it. This interest was borne from the realization that XML's deployment as a Web technology was limited to entirely new technologies (like RSS and later Atom), rather than as a replacement for existing deployed technologies (like HTML).

A proof of concept to show that it was possible to extend HTML4's forms to provide many of the features that XForms 1.0 introduced, without requiring browsers to implement rendering engines that were incompatible with existing HTML Web pages, was the first result of this renewed interest. At this early stage, while the draft was already publicly available, and input was already being solicited from all sources, the specification was only under Opera Software's copyright.

The idea that HTML's evolution should be reopened was tested at a W3C workshop in 2004, where some of the principles that underlie the HTML5 work (described below), as well as the aforementioned early draft proposal covering just forms-related features, were presented to the W3C jointly by Mozilla and Opera. The proposal was rejected on the grounds that the proposal conflicted with the previously chosen direction for the Web's evolution; the W3C staff and membership voted to continue developing XML-based replacements instead.

Shortly thereafter, Apple, Mozilla, and Opera jointly announced their intent to continue working on the effort under the umbrella of a new venue called the WHATWG. A public mailing list was created, and the draft was moved to the WHATWG site. The copyright was subsequently amended to be jointly owned by all three vendors, and to allow reuse of the specification.

The WHATWG was based on several core principles, in particular that technologies need to be backwards compatible, that specifications and implementations need to match even if this means changing the specification rather than the implementations, and that specifications need to be detailed enough that implementations can achieve complete interoperability without reverse-engineering each other.

The latter requirement in particular required that the scope of the HTML5 specification include what had previously been specified in three separate documents: HTML4, XHTML1, and DOM2 HTML. It also meant including significantly more detail than had previously been considered the norm.

In 2006, the W3C indicated an interest to participate in the development of HTML5 after all, and in 2007 formed a working group chartered to work with the WHATWG on the development of the HTML5 specification. Apple, Mozilla, and Opera allowed the W3C to publish the specification under the W3C copyright, while keeping a version with the less restrictive license on the WHATWG site.

The HTML specification published by the WHATWG is not identical to this specification. The main differences are that the WHATWG version includes features not included in this W3C version: some features have been omitted as they are considered part of future revisions of HTML, not HTML5; and other features are omitted because at the W3C they are published as separate specifications. There are also some minor differences. For an exact list of differences, please see the WHATWG specification.

A separate document has been published by the W3C HTML working group to document the differences between the HTML specified in this document and the language described in the HTML4 specification. [HTMLDIFF]

1.5 Design notes

It must be admitted that many aspects of HTML appear at first glance to be nonsensical and inconsistent.

HTML, its supporting DOM APIs, as well as many of its supporting technologies, have been developed over a period of several decades by a wide array of people with different priorities who, in many cases, did not know of each other's existence.

Features have thus arisen from many sources, and have not always been designed in especially consistent ways. Furthermore, because of the unique characteristics of the Web, implementation bugs have often become de-facto, and now de-jure, standards, as content is often unintentionally written in ways that rely on them before they can be fixed.

Despite all this, efforts have been made to adhere to certain design goals. These are described in the next few subsections.

1.5.1 Serializability of script execution

To avoid exposing Web authors to the complexities of multithreading, the HTML and DOM APIs are designed such that no script can ever detect the simultaneous execution of other scripts. Even with workers, the intent is that the behavior of implementations can be thought of as completely serializing the execution of all scripts in all browsing contexts.

The navigator.yieldForStorageUpdates() method, in this model, is equivalent to allowing other scripts to run while the calling script is blocked.

1.5.2 Compliance with other specifications

This specification interacts with and relies on a wide variety of other specifications. In certain circumstances, unfortunately, conflicting needs have led to this specification violating the requirements of these other specifications. Whenever this has occurred, the transgressions have each been noted as a "willful violation", and the reason for the violation has been noted.

1.6 HTML vs XHTML

This specification defines an abstract language for describing documents and applications, and some APIs for interacting with in-memory representations of resources that use this language.

There are various concrete syntaxes that can be used to transmit resources that use this abstract language, two of which are defined in this specification.

The first such concrete syntax is the HTML syntax. This is the format suggested for most authors. It is compatible with most legacy Web browsers. If a document is transmitted with the text/html MIME type, then it will be processed as an HTML document by Web browsers. This specification defines version 5 of the HTML syntax, known as "HTML5".

The second concrete syntax is the XHTML syntax, which is an application of XML. When a document is transmitted with an XML MIME type, such as application/xhtml+xml, then it is treated as an XML document by Web browsers, to be parsed by an XML processor. Authors are reminded that the processing for XML and HTML differs; in particular, even minor syntax errors will prevent a document labeled as XML from being rendered fully, whereas they would be ignored in the HTML syntax. This specification defines version 5 of the XHTML syntax, known as "XHTML5".

The DOM, the HTML syntax, and the XHTML syntax cannot all represent the same content. For example, namespaces cannot be represented using the HTML syntax, but they are supported in the DOM and in the XHTML syntax. Similarly, documents that use the noscript feature can be represented using the HTML syntax, but cannot be represented with the DOM or in the XHTML syntax. Comments that contain the string "-->" can only be represented in the DOM, not in the HTML and XHTML syntaxes.

1.7 Structure of this specification

1.7.1 How to read this specification

This specification should be read like all other specifications. First, it should be read cover-to-cover, multiple times. Then, it should be read backwards at least once. Then it should be read by picking random sections from the contents list and following all the cross-references.

As described in the conformance requirements section below, this specification describes conformance criteria for a variety of conformance classes. In particular, there are conformance requirements that apply to producers, for example authors and the documents they create, and there are conformance requirements that apply to consumers, for example Web browsers. They can be distinguished by what they are requiring: a requirement on a producer states what is allowed, while a requirement on a consumer states how software is to act.

1.7.2 Typographic conventions

The defining instance of a term is marked up like this. Uses of that term are marked up like this or like this.

The defining instance of an element, attribute, or API is marked up like this. References to that element, attribute, or API are marked up like this.

1.8 A quick introduction to HTML

HTML documents consist of a tree of elements and text. Each element is denoted in the source by a start tag, such as "<body>", and an end tag, such as "</body>". (Certain start tags and end tags can in certain cases be omitted and are implied by other tags.)

Tags have to be nested such that elements are all completely within each other, without overlapping:

This specification defines a set of elements that can be used in HTML, along with rules about the ways in which the elements can be nested.

Elements can have attributes, which control how the elements work. In the example below, there is a hyperlink, formed using the a element and its href attribute:

Attributes are placed inside the start tag, and consist of a name and a value, separated by an "=" character. The attribute value can remain unquoted if it doesn't contain space characters or any of " ' ` = < or >. Otherwise, it has to be quoted using either single or double quotes. The value, along with the "=" character, can be omitted altogether if the value is the empty string.

HTML user agents (e.g. Web browsers) then parse this markup, turning it into a DOM (Document Object Model) tree. A DOM tree is an in-memory representation of a document.

DOM trees contain several kinds of nodes, in particular a DOCTYPE node, elements, text nodes, and comment nodes.

The root element of this tree is the html element, which is the element always found at the root of HTML documents. It contains two elements, head and body, as well as a text node between them.

There are many more text nodes in the DOM tree than one would initially expect, because the source contains a number of spaces (represented here by "â£") and line breaks ("âŽ") that all end up as text nodes in the DOM. However, for historical reasons not all of the spaces and line breaks in the original markup appear in the DOM. In particular, all the whitespace before head start tag ends up being dropped silently, and all the whitespace after the body end tag ends up placed at the end of the body.

The head element contains a title element, which itself contains a text node with the text "Sample page". Similarly, the body element contains an h1 element, a p element, and a comment.

This DOM tree can be manipulated from scripts in the page. Scripts (typically in JavaScript) are small programs that can be embedded using the script element or using event handler content attributes. For example, here is a form with a script that sets the value of the form's output element to say "Hello World":

Each element in the DOM tree is represented by an object, and these objects have APIs so that they can be manipulated. For instance, a link (e.g. the a element in the tree above) can have its "href" attribute changed in several ways:

Since DOM trees are used as the way to represent HTML documents when they are processed and presented by implementations (especially interactive implementations like Web browsers), this specification is mostly phrased in terms of DOM trees, instead of the markup described above.

HTML documents represent a media-independent description of interactive content. HTML documents might be rendered to a screen, or through a speech synthesizer, or on a braille display. To influence exactly how such rendering takes place, authors can use a styling language such as CSS.

For more details on how to use HTML, authors are encouraged to consult tutorials and guides. Some of the examples included in this specification might also be of use, but the novice author is cautioned that this specification, by necessity, defines the language with a level of detail that might be difficult to understand at first.

1.8.1 Writing secure applications with HTML

When HTML is used to create interactive sites, care needs to be taken to avoid introducing vulnerabilities through which attackers can compromise the integrity of the site itself or of the site's users.

A comprehensive study of this matter is beyond the scope of this document, and authors are strongly encouraged to study the matter in more detail. However, this section attempts to provide a quick introduction to some common pitfalls in HTML application development.

The security model of the Web is based on the concept of "origins", and correspondingly many of the potential attacks on the Web involve cross-origin actions. [ORIGIN]

1.8.2 Common pitfalls to avoid when using the scripting APIs

Scripts in HTML have "run-to-completion" semantics, meaning that the browser will generally run the script uninterrupted before doing anything else, such as firing further events or continuing to parse the document.

On the other hand, parsing of HTML files happens asynchronously and incrementally, meaning that the parser can pause at any point to let scripts run. This is generally a good thing, but it does mean that authors need to be careful to avoid hooking event handlers after the events could have possibly fired.

There are two techniques for doing this reliably: use event handler content attributes, or create the element and add the event handlers in the same script. The latter is safe because, as mentioned earlier, scripts are run to completion before further events can fire.

1.9 Conformance requirements for authors

Unlike previous versions of the HTML specification, this specification defines in some detail the required processing for invalid documents as well as valid documents.

However, even though the processing of invalid content is in most cases well-defined, conformance requirements for documents are still important: in practice, interoperability (the situation in which all implementations process particular content in a reliable and identical or equivalent way) is not the only goal of document conformance requirements. This section details some of the more common reasons for still distinguishing between a conforming document and one with errors.

1.9.1 Presentational markup

The majority of presentational features from previous versions of HTML are no longer allowed. Presentational markup in general has been found to have a number of problems:

For those reasons, presentational markup has been removed from HTML in this version. This change should not come as a surprise; HTML4 deprecated presentational markup many years ago and provided a mode (HTML4 Transitional) to help authors move away from presentational markup; later, XHTML 1.1 went further and obsoleted those features altogether.

The only remaining presentational markup features in HTML are the style attribute and the style element. Use of the style attribute is somewhat discouraged in production environments, but it can be useful for rapid prototyping (where its rules can be directly moved into a separate style sheet later) and for providing specific styles in unusual cases where a separate style sheet would be inconvenient. Similarly, the style element can be useful in syndication or for page-specific styles, but in general an external style sheet is likely to be more convenient when the styles apply to multiple pages.

It is also worth noting that some elements that were previously presentational have been redefined in this specification to be media-independent: b, i, hr, s, small, and u.

1.9.2 Syntax errors

Some authors find it helpful to be in the practice of always quoting all attributes and always including all optional tags, preferring the consistency derived from such custom over the minor benefits of terseness afforded by making use of the flexibility of the HTML syntax. To aid such authors, conformance checkers can provide modes of operation wherein such conventions are enforced.

1.9.3 Restrictions on content models and on attribute values

Beyond the syntax of the language, this specification also places restrictions on how elements and attributes can be specified. These restrictions are present for similar reasons:

1.10 Recommended reading

2 Common infrastructure

2.1 Terminology

This specification refers to both HTML and XML attributes and IDL attributes, often in the same context. When it is not clear which is being referred to, they are referred to as content attributes for HTML and XML attributes, and IDL attributes for those defined on IDL interfaces. Similarly, the term "properties" is used for both JavaScript object properties and CSS properties. When these are ambiguous they are qualified as object properties and CSS properties respectively.

Generally, when the specification states that a feature applies to the HTML syntax or the XHTML syntax, it also includes the other. When a feature specifically only applies to one of the two languages, it is called out by explicitly stating that it does not apply to the other format, as in "for HTML, ... (this does not apply to XHTML)".

This specification uses the term document to refer to any use of HTML, ranging from short static documents to long essays or reports with rich multimedia, as well as to fully-fledged interactive applications. The term is used to refer both to Document objects and their descendant DOM trees, and to serialized byte streams using the HTML syntax or XHTML syntax, depending on context.

In the context of the DOM structures, the terms HTML document and XML document are used as defined in the DOM Core specification, and refer specifically to two different modes that Document objects can find themselves in. [DOMCORE] (Such uses are always hyperlinked to their definition.)

In the context of byte streams, the term HTML document refers to resources labeled as text/html, and the term XML document refers to resources labeled with an XML MIME type.

The term XHTML document is used to refer to both Documents in the XML document mode that contains element nodes in the HTML namespace, and byte streams labeled with an XML MIME type that contain elements from the HTML namespace, depending on context.

For simplicity, terms such as shown, displayed, and visible might sometimes be used when referring to the way a document is rendered to the user. These terms are not meant to imply a visual medium; they must be considered to apply to other media in equivalent ways.

The term "transparent black" refers to the color with red, green, blue, and alpha channels all set to zero.

2.1.1 Resources

The specification uses the term supported when referring to whether a user agent has an implementation capable of decoding the semantics of an external resource. A format or type is said to be supported if the implementation can process an external resource of that format or type without critical aspects of the resource being ignored. Whether a specific resource is supported can depend on what features of the resource's format are in use.

For example, a PNG image would be considered to be in a supported format if its pixel data could be decoded and rendered, even if, unbeknownst to the implementation, the image also contained animation data.

A MPEG4 video file would not be considered to be in a supported format if the compression format used was not supported, even if the implementation could determine the dimensions of the movie from the file's metadata.

What some specifications, in particular the HTTP and URI specifications, refer to as a representation is referred to in this specification as a resource. [HTTP] [RFC3986]

The term MIME type is used to refer to what is sometimes called an Internet media type in protocol literature. The term media type in this specification is used to refer to the type of media intended for presentation, as used by the CSS specifications. [RFC2046] [MQ]

A string is a valid MIME type if it matches the media-type rule defined in section 3.7 "Media Types" of RFC 2616. In particular, a valid MIME type may include MIME type parameters. [HTTP]

A string is a valid MIME type with no parameters if it matches the media-type rule defined in section 3.7 "Media Types" of RFC 2616, but does not contain any U+003B SEMICOLON characters (;). In other words, if it consists only of a type and subtype, with no MIME Type parameters. [HTTP]

A resource's critical subresources are those that the resource needs to have available to be correctly processed. Which resources are considered critical or not is defined by the specification that defines the resource's format. For CSS resources, only @import rules introduce critical subresources; other resources, e.g. fonts or backgrounds, are not.

2.1.2 XML

To ease migration from HTML to XHTML, UAs conforming to this specification will place elements in HTML in the http://www.w3.org/1999/xhtml namespace, at least for the purposes of the DOM and CSS. The term "HTML elements", when used in this specification, refers to any element in that namespace, and thus refers to both HTML and XHTML elements.

Except where otherwise stated, all elements defined or mentioned in this specification are in the HTML namespace ("http://www.w3.org/1999/xhtml"), and all attributes defined or mentioned in this specification have no namespace.

The term element type is used to refer to the class of elements have a given local name and namespace. For example, button elements are elements with the element type button, meaning they have the local name "button" and (implicitly as defined above) the HTML namespace.

Attribute names are said to be XML-compatible if they match the Name production defined in XML, they contain no U+003A COLON characters (:), and their first three characters are not an ASCII case-insensitive match for the string "xml". [XML]

The term XML MIME type is used to refer to the MIME types text/xml, application/xml, and any MIME type whose subtype ends with the four characters "+xml". [RFC3023]

2.1.3 DOM trees

The root element of a Document object is that Document's first element child, if any. If it does not have one then the Document has no root element.

The term root element, when not referring to a Document object's root element, means the furthest ancestor element node of whatever node is being discussed, or the node itself if it has no ancestors. When the node is a part of the document, then the node's root element is indeed the document's root element; however, if the node is not currently part of the document tree, the root element will be an orphaned node.

When an element's root element is the root element of a Document object, it is said to be in a Document. An element is said to have been inserted into a document when its root element changes and is now the document's root element. Analogously, an element is said to have been removed from a document when its root element changes from being the document's root element to being another element.

The Document of a content attribute is the Document of the attribute's element.

The term tree order means a pre-order, depth-first traversal of DOM nodes involved (through the


parentNode

/childNodes relationship).

When it is stated that some element or attribute is ignored, or treated as some other value, or handled as if it was something else, this refers only to the processing of the node after it is in the DOM.

The term text node refers to any Text node, including


CDATASection

nodes; specifically, any


Node

with node type TEXT_NODE (3) or CDATA_SECTION_NODE (4). [DOMCORE]

A content attribute is said to change value only if its new value is different than its previous value; setting an attribute to a value it already has does not change it.

The term empty, when used of an attribute value, text node, or string, means that the length of the text is zero (i.e. not even containing spaces or control characters).

2.1.4 Scripting

The construction "a Foo object", where Foo is actually an interface, is sometimes used instead of the more accurate "an object implementing the interface Foo".

An IDL attribute is said to be getting when its value is being retrieved (e.g. by author script), and is said to be setting when a new value is assigned to it.

If a DOM object is said to be live, then the attributes and methods on that object operate on the actual underlying data, not a snapshot of the data.

In the contexts of events, the terms fire and dispatch are used as defined in the DOM Core specification: firing an event means to create and dispatch it, and dispatching an event means to follow the steps that propagate the event through the tree. The term trusted event is used to refer to events whose


isTrusted

attribute is initialized to true. [DOMCORE]

2.1.5 Plugins

The term plugin refers to a user-agent defined set of content handlers used by the user agent that can take part in the user agent's rendering of a Document object, but that neither act as child browsing contexts of the Document nor introduce any


Node

objects to the Document's DOM.

Typically such content handlers are provided by third parties, though a user agent can also designate built-in content handlers as plugins.

One example of a plugin would be a PDF viewer that is instantiated in a browsing context when the user navigates to a PDF file. This would count as a plugin regardless of whether the party that implemented the PDF viewer component was the same as that which implemented the user agent itself. However, a PDF viewer application that launches separate from the user agent (as opposed to using the same interface) is not a plugin by this definition.

This specification does not define a mechanism for interacting with plugins, as it is expected to be user-agent- and platform-specific. Some UAs might opt to support a plugin mechanism such as the Netscape Plugin API; others might use remote content converters or have built-in support for certain types. Indeed, this specification doesn't require user agents to support plugins at all. [NPAPI]

For example, a secured plugin would prevent its contents from creating pop-up windows when the plugin is instantiated inside a sandboxed iframe.

2.1.6 Character encodings

The preferred MIME name of a character encoding is the name or alias labeled as "preferred MIME name" in the IANA Character Sets registry, if there is one, or the encoding's name, if none of the aliases are so labeled. [IANACHARSET]

An ASCII-compatible character encoding is a single-byte or variable-length encoding in which the bytes 0x09, 0x0A, 0x0C, 0x0D, 0x20 - 0x22, 0x26, 0x27, 0x2C - 0x3F, 0x41 - 0x5A, and 0x61 - 0x7A, ignoring bytes that are the second and later bytes of multibyte sequences, all correspond to single-byte sequences that map to the same Unicode characters as those bytes in ANSI_X3.4-1968 (US-ASCII). [RFC1345]

This includes such encodings as Shift_JIS, HZ-GB-2312, and variants of ISO-2022, even though it is possible in these encodings for bytes like 0x70 to be part of longer sequences that are unrelated to their interpretation as ASCII. It excludes such encodings as UTF-7, UTF-16, GSM03.38, and EBCDIC variants.

The term a UTF-16 encoding refers to any variant of UTF-16: self-describing UTF-16 with a BOM, ambiguous UTF-16 without a BOM, raw UTF-16LE, and raw UTF-16BE. [RFC2781]

The term code unit is used as defined in the Web IDL specification: a 16 bit unsigned integer, the smallest atomic component of a DOMString. (This is a narrower definition than the one used in Unicode.) [WEBIDL]

The term Unicode code point means a Unicode scalar value where possible, and an isolated surrogate code point when not. When a conformance requirement is defined in terms of characters or Unicode code points, a pair of code units consisting of a high surrogate followed by a low surrogate must be treated as the single code point represented by the surrogate pair, but isolated surrogates must each be treated as the single code point with the value of the surrogate. [UNICODE]

In this specification, the term character, when not qualified as Unicode character, is synonymous with the term Unicode code point.

The term Unicode character is used to mean a Unicode scalar value (i.e. any Unicode code point that is not a surrogate code point). [UNICODE]

This complexity results from the historical decision to define the DOM API in terms of 16 bit (UTF-16) code units, rather than in terms of Unicode characters.

2.2 Conformance requirements

All diagrams, examples, and notes in this specification are non-normative, as are all sections explicitly marked non-normative. Everything else in this specification is normative.

The key words "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in the normative parts of this document are to be interpreted as described in RFC2119. For readability, these words do not appear in all uppercase letters in this specification. [RFC2119]

2.2.1 Extensibility

HTML has a wide number of extensibility mechanisms that can be used for adding semantics in a safe manner:

When adding new reflecting IDL attributes corresponding to content attributes of the form "x-vendor-feature", the IDL attribute should be named "vendorFeature" (i.e. the "x" is dropped from the IDL attribute's name).

2.3 Case-sensitivity and string comparison

Comparing two strings in a case-sensitive manner means comparing them exactly, code point for code point.

Comparing two strings in an ASCII case-insensitive manner means comparing them exactly, code point for code point, except that the characters in the range U+0041 to U+005A (i.e. LATIN CAPITAL LETTER A to LATIN CAPITAL LETTER Z) and the corresponding characters in the range U+0061 to U+007A (i.e. LATIN SMALL LETTER A to LATIN SMALL LETTER Z) are considered to also match.

Comparing two strings in a compatibility caseless manner means using the Unicode compatibility caseless match operation to compare the two strings. [UNICODE]

Except where otherwise stated, string comparisons must be performed in a case-sensitive manner.

A string pattern is a prefix match for a string s when pattern is not longer than s and truncating s to pattern's length leaves the two strings as matches of each other.

2.4 Common microsyntaxes

There are various places in HTML that accept particular data types, such as dates or numbers. This section describes what the conformance criteria for content in those formats is, and how to parse them.

The space characters, for the purposes of this specification, are U+0020 SPACE, U+0009 CHARACTER TABULATION (tab), U+000A LINE FEED (LF), U+000C FORM FEED (FF), and U+000D CARRIAGE RETURN (CR).

The White_Space characters are those that have the Unicode property "White_Space" in the Unicode PropList.txt data file. [UNICODE]

This should not be confused with the "White_Space" value (abbreviated "WS") of the "Bidi_Class" property in the Unicode.txt data file.

2.4.2 Boolean attributes

A number of attributes are boolean attributes. The presence of a boolean attribute on an element represents the true value, and the absence of the attribute represents the false value.

If the attribute is present, its value must either be the empty string or a value that is an ASCII case-insensitive match for the attribute's canonical name, with no leading or trailing whitespace.

The values "true" and "false" are not allowed on boolean attributes. To represent a false value, the attribute has to be omitted altogether.

2.4.3 Keywords and enumerated attributes

Some attributes are defined as taking one of a finite set of keywords. Such attributes are called enumerated attributes. The keywords are each defined to map to a particular state (several keywords might map to the same state, in which case some of the keywords are synonyms of each other; additionally, some of the keywords can be said to be non-conforming, and are only in the specification for historical reasons). In addition, two default states can be given. The first is the invalid value default, the second is the missing value default.

If an enumerated attribute is specified, the attribute's value must be an ASCII case-insensitive match for one of the given keywords that are not said to be non-conforming, with no leading or trailing whitespace.

When the attribute is specified, if its value is an ASCII case-insensitive match for one of the given keywords then that keyword's state is the state that the attribute represents. If the attribute value matches none of the given keywords, but the attribute has an invalid value default, then the attribute represents that state. Otherwise, if the attribute value matches none of the keywords but there is a missing value default state defined, then that is the state represented by the attribute. Otherwise, there is no default, and invalid values must be ignored.

When the attribute is not specified, if there is a missing value default state defined, then that is the state represented by the (missing) attribute. Otherwise, the absence of the attribute means that there is no state represented.

2.4.4 Numbers

2.4.4.1 Signed integers

A string is a valid integer if it consists of one or more characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), optionally prefixed with a U+002D HYPHEN-MINUS character (-).

A valid integer without a U+002D HYPHEN-MINUS (-) prefix represents the number that is represented in base ten by that string of digits. A valid integer with a U+002D HYPHEN-MINUS (-) prefix represents the number represented in base ten by the string of digits that follows the U+002D HYPHEN-MINUS, subtracted from zero.

2.4.4.2 Non-negative integers

A string is a valid non-negative integer if it consists of one or more characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9).

A valid non-negative integer represents the number that is represented in base ten by that string of digits.

2.4.4.3 Floating-point numbers

A valid floating point number represents the number obtained by multiplying the significand by ten raised to the power of the exponent, where the significand is the first number, interpreted as base ten (including the decimal point and the number after the decimal point, if any, and interpreting the significand as a negative number if the whole string starts with a U+002D HYPHEN-MINUS character (-) and the number is not zero), and where the exponent is the number after the E, if any (interpreted as a negative number if there is a U+002D HYPHEN-MINUS character (-) between the E and the number and the number is not zero, or else ignoring a U+002B PLUS SIGN character (+) between the E and the number if there is one). If there is no E, then the exponent is treated as zero.

2.4.4.4 Lists of integers

A valid list of integers is a number of valid integers separated by U+002C COMMA characters, with no other characters (e.g. no space characters). In addition, there might be restrictions on the number of integers that can be given, or on the range of values allowed.

2.4.5 Dates and times

In the algorithms below, the number of days in month month of year year is: 31 if month is 1, 3, 5, 7, 8, 10, or 12; 30 if month is 4, 6, 9, or 11; 29 if month is 2 and year is a number divisible by 400, or if year is a number divisible by 4 but not by 100; and 28 otherwise. This takes into account leap years in the Gregorian calendar. [GREGORIAN]

The digits in the date and time syntaxes defined in this section must be characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), used to express numbers in base ten.

2.4.5.1 Months

A month consists of a specific proleptic Gregorian date with no time-zone information and no date information beyond a year and a month. [GREGORIAN]

A string is a valid month string representing a year year and month month if it consists of the following components in the given order:

2.4.5.2 Dates

A date consists of a specific proleptic Gregorian date with no time-zone information, consisting of a year, a month, and a day. [GREGORIAN]

A string is a valid date string representing a year year, month month, and day day if it consists of the following components in the given order:

2.4.5.3 Yearless dates

A string is a valid yearless date string representing a month month and a day day if it consists of the following components in the given order:

In other words, if the month is "02", meaning February, then the day can be 29, as if the year was a leap year.

2.4.5.4 Times

A time consists of a specific time with no time-zone information, consisting of an hour, a minute, a second, and a fraction of a second.

A string is a valid time string representing an hour hour, a minute minute, and a second second if it consists of the following components in the given order:

2.4.5.5 Local dates and times

A local date and time consists of a specific proleptic Gregorian date, consisting of a year, a month, and a day, and a time, consisting of an hour, a minute, a second, and a fraction of a second, but expressed without a time zone. [GREGORIAN]

A string is a valid local date and time string representing a date and time if it consists of the following components in the given order:

A string is a valid normalized local date and time string representing a date and time if it consists of the following components in the given order:

2.4.5.6 Time zones

A string is a valid time-zone offset string representing a time-zone offset if it consists of either:

This format allows for time-zone offsets from -23:59 to +23:59. In practice, however, the range of offsets of actual time zones is -12:00 to +14:00, and the minutes component of offsets of actual time zones is always either 00, 30, or 45.

See also the usage notes and examples in the global date and time section below for details on using time-zone offsets with historical times that predate the formation of formal time zones.

2.4.5.7 Global dates and times

A global date and time consists of a specific proleptic Gregorian date, consisting of a year, a month, and a day, and a time, consisting of an hour, a minute, a second, and a fraction of a second, expressed with a time-zone offset, consisting of a signed number of hours and minutes. [GREGORIAN]

A string is a valid global date and time string representing a date, time, and a time-zone offset if it consists of the following components in the given order:

Times in dates before the formation of UTC in the mid twentieth century must be expressed and interpreted in terms of UT1 (contemporary Earth solar time at the 0Â° longitude), not UTC (the approximation of UT1 that ticks in SI seconds). Time before the formation of time zones must be expressed and interpeted as UT1 times with explicit time zones that approximate the contemporary difference between the appropriate local time and the time observed at the location of Greenwich, London.

A string is a valid normalized forced-UTC global date and time string representing a date, time, and a time-zone offset if it consists of the following components in the given order:

2.4.5.8 Weeks

A week consists of a week-year number and a week number representing a seven-day period starting on a Monday. Each week-year in this calendaring system has either 52 or 53 such seven-day periods, as defined below. The seven-day period starting on the Gregorian date Monday December 29th 1969 (1969-12-29) is defined as week number 1 in week-year 1970. Consecutive weeks are numbered sequentially. The week before the number 1 week in a week-year is the last week in the previous week-year, and vice versa. [GREGORIAN]

A week-year with a number year has 53 weeks if it corresponds to either a year year in the proleptic Gregorian calendar that has a Thursday as its first day (January 1st), or a year year in the proleptic Gregorian calendar that has a Wednesday as its first day (January 1st) and where year is a number divisible by 400, or a number divisible by 4 but not by 100. All other week-years have 52 weeks.

The week number of the last day of a week-year with 53 weeks is 53; the week number of the last day of a week-year with 52 weeks is 52.

The week-year number of a particular day can be different than the number of the year that contains that day in the proleptic Gregorian calendar. The first week in a week-year y is the week that contains the first Thursday of the Gregorian year y.

A string is a valid week string representing a week-year year and week week if it consists of the following components in the given order:

2.4.5.9 Durations

Since months and seconds are not comparable (a month is not a precise number of seconds, but is instead a period whose exact length depends on the precise day from which it is measured) a duration as defined in this specification cannot include months (or years, which are equivalent to twelve months). Only durations that describe a specific number of seconds can be described.

A string is a valid duration string representing a duration t if it consists of either of the following:

2.4.5.10 Vaguer moments in time

A string is a valid date string with optional time if it is also one of the following:

2.4.6 Colors

A simple color consists of three 8-bit numbers in the range 0..255, representing the red, green, and blue components of the color respectively, in the sRGB color space. [SRGB]

A string is a valid simple color if it is exactly seven characters long, and the first character is a U+0023 NUMBER SIGN character (#), and the remaining six characters are all in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), U+0041 LATIN CAPITAL LETTER A to U+0046 LATIN CAPITAL LETTER F, U+0061 LATIN SMALL LETTER A to U+0066 LATIN SMALL LETTER F, with the first two digits representing the red component, the middle two digits representing the green component, and the last two digits representing the blue component, in hexadecimal.

A string is a valid lowercase simple color if it is a valid simple color and doesn't use any characters in the range U+0041 LATIN CAPITAL LETTER A to U+0046 LATIN CAPITAL LETTER F.

2.4.7 Space-separated tokens

A set of space-separated tokens is a string containing zero or more words (known as tokens) separated by one or more space characters, where words consist of any string of one or more characters, none of which are space characters.

An unordered set of unique space-separated tokens is a set of space-separated tokens where none of the tokens are duplicated.

An ordered set of unique space-separated tokens is a set of space-separated tokens where none of the tokens are duplicated but where the order of the tokens is meaningful.

Sets of space-separated tokens sometimes have a defined set of allowed values. When a set of allowed values is defined, the tokens must all be from that list of allowed values; other values are non-conforming. If no such set of allowed values is provided, then all values are conforming.

How tokens in a set of space-separated tokens are to be compared (e.g. case-sensitively or not) is defined on a per-set basis.

2.4.8 Comma-separated tokens

A set of comma-separated tokens is a string containing zero or more tokens each separated from the next by a single U+002C COMMA character (,), where tokens consist of any string of zero or more characters, neither beginning nor ending with space characters, nor containing any U+002C COMMA characters (,), and optionally surrounded by space characters.

For instance, the string " a ,b,,d d " consists of four tokens: "a", "b", the empty string, and "d d". Leading and trailing whitespace around each token doesn't count as part of the token, and the empty string can be a token.

Sets of comma-separated tokens sometimes have further restrictions on what consists a valid token. When such restrictions are defined, the tokens must all fit within those restrictions; other values are non-conforming. If no such restrictions are specified, then all values are conforming.

2.4.9 References

A valid hash-name reference to an element of type type is a string consisting of a U+0023 NUMBER SIGN character (#) followed by a string which exactly matches the value of the name attribute of an element with type type in the document.

2.4.10 Media queries

A string is a valid media query if it matches the media_query_list production of the Media Queries specification. [MQ]

A string matches the environment of the user if it is the empty string, a string consisting of only space characters, or is a media query that matches the user's environment according to the definitions given in the Media Queries specification. [MQ]

2.5 URLs

This specification defines the term URL, and defines various algorithms for dealing with URLs, because for historical reasons the rules defined by the URI and IRI specifications are not a complete description of what HTML user agents need to implement to be compatible with Web content.

The term "URL" in this specification is used in a manner distinct from the precise technical meaning it is given in RFC 3986. Readers familiar with that RFC will find it easier to read this specification if they pretend the term "URL" as used herein is really called something else altogether. This is a willful violation of RFC 3986. [RFC3986]

2.5.1 Terminology

A string is a valid non-empty URL if it is a valid URL but it is not the empty string.

This specification defines the URL about:legacy-compat as a reserved, though unresolvable, about: URI, for use in DOCTYPEs in HTML documents when needed for compatibility with XML tools. [ABOUT]

2.5.2 Resolving URLs

Resolving a URL is the process of taking a relative URL and obtaining the absolute URL that it implies.

A URL is an absolute URL if resolving it results in the same output regardless of what it is resolved relative to, and that output is not a failure.

An absolute URL is a hierarchical URL if, when resolved and then parsed, there is a character immediately after the <scheme> component and it is a U+002F SOLIDUS character (/).

An absolute URL is an authority-based URL if, when resolved and then parsed, there are two characters immediately after the <scheme> component and they are both U+002F SOLIDUS characters (//).

2.5.3 Interfaces for URL manipulation

An interface that has a complement of URL decomposition IDL attributes has seven attributes with the following definitions:

Input URL	`search` value	Explanation
`http://example.com/`	empty string	No <query> component in input URL.
`http://example.com/?`	`?`	There is a <query> component, but it is empty.
`http://example.com/?test`	`?test`	The <query> component has the value "`test`".
`http://example.com/?test#`	`?test`	The (empty) <fragment> component is not part of the <query> component.

Input	`protocol`	`host`	`hostname`	`port`	`pathname`	`search`	`hash`
`http://example.com/carrot#question%3f`	`http:`	`example.com`	`example.com`	(empty string)	`/carrot`	(empty string)	`#question%3f`
`https://www.example.com:4443?`	`https:`	`www.example.com:4443`	`www.example.com`	`4443`	`/`	`?`	(empty string)

2.5.4 CORS settings attributes

A CORS settings attribute is an enumerated attribute. The following table lists the keywords and states for the attribute â€” the keywords in the left column map to the states in the cell in the second column on the same row as the keyword.

Keyword	State	Brief description
`anonymous`	Anonymous	Cross-origin CORS requests for the element will not have the credentials flag set.
`use-credentials`	Use Credentials	Cross-origin CORS requests for the element will have the credentials flag set.

The empty string is also a valid keyword, and maps to the Anonymous state. The attribute's invalid value default is the Anonymous state. The missing value default, used when the attribute is omitted, is the No CORS state.

2.6 Common DOM interfaces

2.6.1 Reflecting content attributes in IDL attributes

Some IDL attributes are defined to reflect a particular content attribute. This means that on getting, the IDL attribute returns the current value of the content attribute, and on setting, the IDL attribute changes the value of the content attribute to the given value.

2.6.2 Collections

2.6.2.1 HTMLAllCollection

2.6.2.2 HTMLFormControlsCollection

2.6.2.3 HTMLOptionsCollection

The HTMLOptionsCollection interface represents a list of option elements. It is always rooted on a select element and has attributes and methods that manipulate that element's descendants.

2.6.3 DOMStringMap

The


DOMStringMap

interface represents a set of name-value pairs. It exposes these using the scripting language's native mechanisms for property access.

2.6.4 Transferable objects

Some objects support being copied and closed in one operation. This is called transferring the object, and is used in particular to transfer ownership of unsharable or expensive resources across worker boundaries.

2.6.5 DOM feature strings

DOM3 Core defines mechanisms for checking for interface support, and for obtaining implementations of interfaces, using feature strings. [DOMCORE]

Authors are strongly discouraged from using these, as they are notoriously unreliable and imprecise. Authors are encouraged to rely on explicit feature testing or the graceful degradation behavior intrinsic to some of the features in this specification.

2.7 Namespaces

Data mining tools and other user agents that perform operations on content without running scripts, evaluating CSS or XPath expressions, or otherwise exposing the resulting DOM to arbitrary content, may "support namespaces" by just asserting that their DOM node analogues are in certain namespaces, without actually exposing the above strings.

In the HTML syntax, namespace prefixes and namespace declarations do not have the same effect as in XML. For instance, the colon has no special meaning in HTML element names.

3 Semantics, structure, and APIs of HTML documents

3.1 Documents

Every XML and HTML document in an HTML UA is represented by a Document object. [DOMCORE]

Each Document object has a reload override flag that is originally unset. The flag is set by the document.open() and document.write() methods in certain situations. When the flag is set, the Document also has a reload override buffer which is a Unicode string that is used as the source of the document when it is reloaded.

3.1.1 Documents in the DOM

The DOM Core specification defines a Document interface, which this specification extends significantly:

3.1.2 Security

3.1.3 Resource metadata management

In the case of HTTP, the referrer IDL attribute will match the Referer (sic) header that was sent when fetching the current page.

Typically user agents are configured to not report referrers in the case where the referrer uses an encrypted protocol and the current page does not (e.g. when navigating from an https: page to an http: page).

3.1.4 DOM tree accessors

The html element of a document is the document's root element, if there is one and it's an html element, or null otherwise.

The head element of a document is the first head element that is a child of the html element, if there is one, or null otherwise.

The title element of a document is the first title element in the document (in tree order), if there is one, or null otherwise.

The body element of a document is the first child of the html element that is either a body element or a


frameset

element. If there is no such element, it is null.

The dir attribute on the Document interface is defined along with the dir content attribute.

3.2 Elements

3.2.1 Semantics

Elements, attributes, and attribute values in HTML are defined (by this specification) to have certain meanings (semantics). For example, the ol element represents an ordered list, and the lang attribute represents the language of the content.

These definitions allow HTML processors, such as Web browsers or search engines, to present and use documents and applications in a wide variety of contexts that the author might not have considered.

Authors must not use elements, attributes, or attribute values for purposes other than their appropriate intended semantic purpose, as doing so prevents software from correctly processing the page.

Authors must not use elements, attributes, or attribute values that are not permitted by this specification or other applicable specifications, as doing so makes it significantly harder for the language to be extended in the future.

Through scripting and using other mechanisms, the values of attributes, text, and indeed the entire structure of the document may change dynamically while a user agent is processing it. The semantics of a document at an instant in time are those represented by the state of the document at that instant in time, and the semantics of a document can therefore change over time. User agents update their presentation of the document as this occurs.

HTML has a progress element that describes a progress bar. If its "value" attribute is dynamically updated by a script, the UA would update the rendering to show the progress changing.

3.2.2 Elements in the DOM

The nodes representing HTML elements in the DOM implement, and expose to scripts, the interfaces listed for them in the relevant sections of this specification. This includes HTML elements in XML documents, even when those documents are in another context (e.g. inside an XSLT transform).

Elements in the DOM represent things; that is, they have intrinsic meaning, also known as semantics.

The basic interface, from which all the HTML elements' interfaces inherit, is the HTMLElement interface.

The HTMLElement interface holds methods and attributes related to a number of disparate features, and the members of this interface are therefore described in various different sections of this specification.

3.2.3 Global attributes

The following attributes are common to and may be specified on all HTML elements:

The attributes marked with an asterisk have a different meaning when specified on body elements as those elements expose event handlers of the Window object with the same names.

While these attributes apply to all elements, they are not useful on all elements. For example, only media elements will ever receive a volumechange event fired by the user agent.

Custom data attributes (e.g. data-foldername or data-msgid) can be specified on any HTML element, to store custom data specific to the page.

In HTML documents, elements in the HTML namespace may have an xmlns attribute specified, if, and only if, it has the exact value "http://www.w3.org/1999/xhtml". This does not apply to XML documents.

In HTML, the xmlns attribute has absolutely no effect. It is basically a talisman. It is allowed merely to make migration to and from XHTML mildly easier. When parsed by an HTML parser, the attribute ends up in no namespace, not the "http://www.w3.org/2000/xmlns/" namespace like namespace declaration attributes in XML do.

In XML, an xmlns attribute is part of the namespace declaration mechanism, and an element cannot actually have an xmlns attribute in no namespace specified.

The XML specification also allows the use of the xml:space attribute in the XML namespace on any element in an XML document. This attribute has no effect on HTML elements, as the default behavior in HTML is to preserve whitespace. [XML]

There is no way to serialize the xml:space attribute on HTML elements in the text/html syntax.

To enable assistive technology products to expose a more fine-grained interface than is otherwise possible with HTML elements and attributes, a set of annotations for assistive technology products can be specified (the ARIA role and aria-* attributes).

3.2.3.1 The id attribute

The value must be unique amongst all the IDs in the element's home subtree and must contain at least one character. The value must not contain any space characters.

An element's unique identifier can be used for a variety of purposes, most notably as a way to link to specific parts of a document using fragment identifiers, as a way to target an element when scripting, and as a way to style a specific element from CSS.

3.2.3.2 The title attribute

The title attribute represents advisory information for the element, such as would be appropriate for a tooltip. On a link, this could be the title or a description of the target resource; on an image, it could be the image credit or a description of the image; on a paragraph, it could be a footnote or commentary on the text; on a citation, it could be further information about the source; and so forth. The value is text.

If this attribute is omitted from an element, then it implies that the title attribute of the nearest ancestor HTML element with a title attribute set is also relevant to this element. Setting the attribute overrides this, explicitly stating that the advisory information of any ancestors is not relevant to this element. Setting the attribute to the empty string indicates that the element has no advisory information.

If the title attribute's value contains U+000A LINE FEED (LF) characters, the content is split into multiple lines. Each U+000A LINE FEED (LF) character represents a line break.

Some elements, such as link, abbr, and input, define additional semantics for the title attribute beyond the semantics described above.

3.2.3.3 The lang and xml:lang attributes

The lang attribute (in no namespace) specifies the primary language for the element's contents and for any of the element's attributes that contain text. Its value must be a valid BCP 47 language tag, or the empty string. Setting the attribute to the empty string indicates that the primary language is unknown. [BCP47]

If these attributes are omitted from an element, then the language of this element is the same as the language of its parent element, if any.

Authors must not use the lang attribute in the XML namespace on HTML elements in HTML documents. To ease migration to and from XHTML, authors may specify an attribute in no namespace with no prefix and with the literal localname "xml:lang" on HTML elements in HTML documents, but such attributes must only be specified if a lang attribute in no namespace is also specified, and both attributes must have the same value when compared in an ASCII case-insensitive manner.

The attribute in no namespace with no prefix and with the literal localname "xml:lang" has no effect on language processing.

The lang IDL attribute must reflect the lang content attribute in no namespace.

3.2.3.4 The xml:base attribute (XML only)

3.2.3.5 The dir attribute

The dir attribute specifies the element's text directionality. The attribute is an enumerated attribute with the following keywords and states:

The directionality of an element is either 'ltr' or 'rtl', and is determined as per the first appropriate set of steps from the following list:

The effect of this attribute is primarily on the presentation layer. For example, the rendering section in this specification defines a mapping from this attribute to the CSS 'direction' and 'unicode-bidi' properties, and CSS defines rendering in terms of those properties.

Authors are strongly encouraged to use the dir attribute to indicate text direction rather than using CSS, since that way their documents will continue to render correctly even in the absence of CSS (e.g. as interpreted by search engines).

3.2.3.6 The class attribute

The attribute, if specified, must have a value that is a set of space-separated tokens representing the various classes that the element belongs to.

Assigning classes to an element affects class matching in selectors in CSS, the getElementsByClassName() method in the DOM, and other such features.

There are no additional restrictions on the tokens authors can use in the class attribute, but authors are encouraged to use values that describe the nature of the content, rather than values that describe the desired presentation of the content.

The className and classList IDL attributes must both reflect the class content attribute.

3.2.3.7 The style attribute

All HTML elements may have the style content attribute set. This is a CSS styling attribute as defined by the CSS Styling Attribute Syntax specification. [CSSATTR]

Documents that use style attributes on any of their elements must still be comprehensible and usable if those attributes were removed.

In particular, using the style attribute to hide and show content, or to convey meaning that is otherwise not included in the document, is non-conforming. (To hide and show content, use the hidden attribute.)

3.2.3.8 Embedding custom non-visible data with the data-* attributes

A custom data attribute is an attribute in no namespace whose name starts with the string "data-", has at least one character after the hyphen, is XML-compatible, and contains no characters in the range U+0041 to U+005A (LATIN CAPITAL LETTER A to LATIN CAPITAL LETTER Z).

All attributes on HTML elements in HTML documents get ASCII-lowercased automatically, so the restriction on ASCII uppercase letters doesn't affect such documents.

Custom data attributes are intended to store custom data private to the page or application, for which there are no more appropriate attributes or elements.

These attributes are not intended for use by software that is independent of the site that uses the attributes.

Authors should carefully design such extensions so that when the attributes are ignored and any associated CSS dropped, the page is still usable.

JavaScript libraries may use the custom data attributes, as they are considered to be part of the page on which they are used. Authors of libraries that are reused by many authors are encouraged to include their name in the attribute names, to reduce the risk of clashes. Where it makes sense, library authors are also encouraged to make the exact name used in the attribute names customizable, so that libraries whose authors unknowingly picked the same name can be used on the same page, and so that multiple versions of a particular library can be used on the same page even when those versions are not mutually compatible.

3.2.4 Element definitions

Each element in this specification has a definition that includes the following information:

This is then followed by a description of what the element represents, along with any additional normative conformance criteria that may apply to authors. Examples are sometimes also included.

3.2.4.1 Attributes

Except where otherwise specified, attributes on HTML elements may have any string value, including the empty string. Except where explicitly stated, there is no restriction on what text can be specified in such attributes.

3.2.5 Content models

Each element defined in this specification has a content model: a description of the element's expected contents. An HTML element must have contents that match the requirements described in the element's content model.

The space characters are always allowed between elements. User agents represent these characters between elements in the source markup as text nodes in the DOM. Empty text nodes and text nodes consisting of just sequences of those characters are considered inter-element whitespace.

Inter-element whitespace, comment nodes, and processing instruction nodes must be ignored when establishing whether an element's contents match the element's content model or not, and must be ignored when following algorithms that define document and element semantics.

Thus, an element A is said to be preceded or followed by a second element B if A and B have the same parent node and there are no other element nodes or text nodes (other than inter-element whitespace) between them. Similarly, a node is the only child of an element if that element contains no other nodes other than inter-element whitespace, comment nodes, and processing instruction nodes.

Authors must not use HTML elements anywhere except where they are explicitly allowed, as defined for each element, or as explicitly required by other specifications. For XML compound documents, these contexts could be inside elements from other namespaces, if those elements are defined as providing the relevant contexts.

3.2.5.1 Kinds of content

Each element in HTML falls into zero or more categories that group elements with similar characteristics together. The following broad categories are used in this specification:

Some elements also fall into other categories, which are defined in other parts of this specification.

Other categories are also used for specific purposes, e.g. form controls are specified using a number of categories to define common requirements. Some elements have unique requirements and do not fit into any particular category.

3.2.5.1.1 Metadata content

Metadata content is content that sets up the presentation or behavior of the rest of the content, or that sets up the relationship of the document with other documents, or that conveys other "out of band" information.

Elements from other namespaces whose semantics are primarily metadata-related (e.g. RDF) are also metadata content.

3.2.5.1.2 Flow content

Most elements that are used in the body of documents and applications are categorized as flow content.

3.2.5.1.3 Sectioning content

3.2.5.1.4 Heading content

Heading content defines the header of a section (whether explicitly marked up using sectioning content elements, or implied by the heading content itself).

3.2.5.1.5 Phrasing content

Phrasing content is the text of the document, as well as elements that mark up that text at the intra-paragraph level. Runs of phrasing content form paragraphs.

As a general rule, elements whose content model allows any phrasing content should have either at least one descendant text node that is not inter-element whitespace, or at least one descendant element node that is embedded content. For the purposes of this requirement, nodes that are descendants of del elements must not be counted as contributing to the ancestors of the del element.

Most elements that are categorized as phrasing content can only contain elements that are themselves categorized as phrasing content, not any flow content.

3.2.5.1.6 Embedded content

Embedded content is content that imports another resource into the document, or content from another vocabulary that is inserted into the document.

Elements that are from namespaces other than the HTML namespace and that convey content but not metadata, are embedded content for the purposes of the content models defined in this specification. (For example, MathML, or SVG.)

Some embedded content elements can have fallback content: content that is to be used when the external resource cannot be used (e.g. because it is of an unsupported format). The element definitions state what the fallback is, if any.

3.2.5.1.7 Interactive content

Interactive content is content that is specifically intended for user interaction.

Certain elements in HTML have an activation behavior, which means that the user can activate them. This triggers a sequence of events dependent on the activation mechanism, and normally culminating in a


click

event.

3.2.5.1.8 Palpable content

As a general rule, elements whose content model allows any flow content or phrasing content should have at least one child node that is palpable content and that does not have the hidden attribute specified.

This requirement is not a hard requirement, however, as there are many cases where an element can be empty legitimately, for example when it is used as a placeholder which will later be filled in by a script, or when the element is part of a template and would on most pages be filled in but on some pages is not relevant.

Conformance checkers are encouraged to provide a mechanism for authors to find elements that fail to fulfill this requirement, as an authoring aid.

3.2.5.2 Transparent content models

Some elements are described as transparent; they have "transparent" in the description of their content model. The content model of a transparent element is derived from the content model of its parent element: the elements required in the part of the content model that is "transparent" are the same elements as required in the part of the content model of the parent of the transparent element in which the transparent element finds itself.

In some cases, where transparent elements are nested in each other, the process has to be applied iteratively.

When a transparent element has no parent, then the part of its content model that is "transparent" must instead be treated as accepting any flow content.

3.2.5.3 Paragraphs

The term paragraph as defined in this section is distinct from (though related to) the p element defined later. The paragraph concept defined here is used to describe how to interpret documents.

A paragraph is typically a run of phrasing content that forms a block of text with one or more sentences that discuss a particular topic, as in typography, but can also be used for more general thematic grouping. For instance, an address is also a paragraph, as is a part of a form, a byline, or a stanza in a poem.

Paragraphs in flow content are defined relative to what the document looks like without the a, ins, del, and map elements complicating matters, since those elements, with their hybrid content models, can straddle paragraph boundaries, as shown in the first two examples below.

Generally, having elements straddle paragraph boundaries is best avoided. Maintaining such markup can be difficult.

The p element can be used to wrap individual paragraphs when there would otherwise not be any content other than phrasing content to separate the paragraphs from each other.

3.2.6 Requirements relating to bidirectional-algorithm formatting characters

Text content in HTML elements with child text nodes, and text in attributes of HTML elements that allow free-form text, may contain characters in the range U+202A to U+202E (the bidirectional-algorithm formatting characters). However, the use of these characters is restricted so that any embedding or overrides generated by these characters do not start and end with different parent elements, and so that all such embeddings and overrides are explicitly terminated by a U+202C POP DIRECTIONAL FORMATTING character. This helps reduce incidences of text being reused in a manner that has unforeseen effects on the bidirectional algorithm.

Any strings that, as described above, are bidirectional-algorithm formatting character ranges must match the string production in the following ABNF, the character set for which is Unicode. [ABNF]

Authors are encouraged to use the dir attribute, the bdo element, and the bdi element, rather than maintaining the bidirectional-algorithm formatting characters manually. The bidirectional-algorithm formatting characters interact poorly with CSS.

3.2.7 WAI-ARIA

Authors may use the ARIA role and aria-* attributes on HTML elements, in accordance with the requirements described in the ARIA specifications, except where these conflict with the strong native semantics described below. These exceptions are intended to prevent authors from making assistive technology products report nonsensical states that do not represent the actual state of the document. [ARIA]

The following table defines the strong native semantics and corresponding default implicit ARIA semantics that apply to HTML elements. Each language feature (element or attribute) in a cell in the first column implies the ARIA semantics (role, states, and/or properties) given in the cell in the second column of the same row.

Language feature	Strong native semantics and default implied ARIA semantics
`area` element that creates a hyperlink	`link` role
`base` element	No role
`datalist` element	`listbox` role, with the `aria-multiselectable` property set to "false"
`details` element	`aria-expanded` state set to "true" if the element's `open` attribute is present, and set to "false" otherwise
`head` element	No role
`hgroup` element	`heading` role, with the `aria-level` property set to the element's outline depth
`hr` element	`separator` role
`html` element	No role
`img` element whose `alt` attribute's value is empty	`presentation` role
`input` element with a `type` attribute in the Checkbox state	`aria-checked` state set to "mixed" if the element's `indeterminate` IDL attribute is true, or "true" if the element's checkedness is true, or "false" otherwise
`input` element with a `type` attribute in the Color state	No role
`input` element with a `type` attribute in the Date state	No role, with the `aria-readonly` property set to "true" if the element has a `readonly` attribute
`input` element with a `type` attribute in the Date and Time state	No role, with the `aria-readonly` property set to "true" if the element has a `readonly` attribute
`input` element with a `type` attribute in the Local Date and Time state	No role, with the `aria-readonly` property set to "true" if the element has a `readonly` attribute
`input` element with a `type` attribute in the E-mail state with no suggestions source element	`textbox` role, with the `aria-readonly` property set to "true" if the element has a `readonly` attribute
`input` element with a `type` attribute in the File Upload state	No role
`input` element with a `type` attribute in the Hidden state	No role
`input` element with a `type` attribute in the Month state	No role, with the `aria-readonly` property set to "true" if the element has a `readonly` attribute
`input` element with a `type` attribute in the Number state	`spinbutton` role, with the `aria-readonly` property set to "true" if the element has a `readonly` attribute, the `aria-valuemax` property set to the element's maximum, the `aria-valuemin` property set to the element's minimum, and, if the result of applying the rules for parsing floating point number values to the element's value is a number, with the `aria-valuenow` property set to that number
`input` element with a `type` attribute in the Password state	`textbox` role, with the `aria-readonly` property set to "true" if the element has a `readonly` attribute
`input` element with a `type` attribute in the Radio Button state	`aria-checked` state set to "true" if the element's checkedness is true, or "false" otherwise
`input` element with a `type` attribute in the Range state	`slider` role, with the `aria-valuemax` property set to the element's maximum, the `aria-valuemin` property set to the element's minimum, and the `aria-valuenow` property set to the result of applying the rules for parsing floating point number values to the element's value, if that results in a number, or the default value otherwise
`input` element with a `type` attribute in the Reset Button state	`button` role
`input` element with a `type` attribute in the Search state with no suggestions source element	`textbox` role, with the `aria-readonly` property set to "true" if the element has a `readonly` attribute
`input` element with a `type` attribute in the Submit Button state	`button` role
`input` element with a `type` attribute in the Telephone state with no suggestions source element	`textbox` role, with the `aria-readonly` property set to "true" if the element has a `readonly` attribute
`input` element with a `type` attribute in the Text state with no suggestions source element	`textbox` role, with the `aria-readonly` property set to "true" if the element has a `readonly` attribute
`input` element with a `type` attribute in the Text, Search, Telephone, URL, or E-mail states with a suggestions source element	`combobox` role, with the `aria-owns` property set to the same value as the `list` attribute, and the `aria-readonly` property set to "true" if the element has a `readonly` attribute
`input` element with a `type` attribute in the Time state	No role, with the `aria-readonly` property set to "true" if the element has a `readonly` attribute
`input` element with a `type` attribute in the URL state with no suggestions source element	`textbox` role, with the `aria-readonly` property set to "true" if the element has a `readonly` attribute
`input` element with a `type` attribute in the Week state	No role, with the `aria-readonly` property set to "true" if the element has a `readonly` attribute
`input` element that is required	The `aria-required` state set to "true"
`keygen` element	No role
`label` element	No role
`link` element that creates a hyperlink	`link` role
`menu` element with a `type` attribute in the context menu state	No role
`menu` element with a `type` attribute in the list state	`menu` role
`menu` element with a `type` attribute in the toolbar state	`toolbar` role
`meta` element	No role
`meter` element	No role
`nav` element	`navigation` role
`noscript` element	No role
`optgroup` element	No role
`option` element that is in a list of options or that represents a suggestion in a `datalist` element	`option` role, with the `aria-selected` state set to "true" if the element's selectedness is true, or "false" otherwise.
`param` element	No role
`progress` element	`progressbar` role, with, if the progress bar is determinate, the `aria-valuemax` property set to the maximum value of the progress bar, the `aria-valuemin` property set to zero, and the `aria-valuenow` property set to the current value of the progress bar
`script` element	No role
`select` element with a `multiple` attribute	`listbox` role, with the `aria-multiselectable` property set to "true"
`select` element with no `multiple` attribute	`listbox` role, with the `aria-multiselectable` property set to "false"
`select` element with a `required` attribute	The `aria-required` state set to "true"
`source` element	No role
`style` element	No role
`summary` element	No role
`textarea` element	`textbox` role, with the `aria-multiline` property set to "true", and the `aria-readonly` property set to "true" if the element has a `readonly` attribute
`textarea` element with a `required` attribute	The `aria-required` state set to "true"
`title` element	No role
An element that defines a command, whose Type facet is "checkbox", and that is a descendant of a `menu` element whose `type` attribute in the list state	`menuitemcheckbox` role, with the `aria-checked` state set to "true" if the command's Checked State facet is true, and "false" otherwise
An element that defines a command, whose Type facet is "command", and that is a descendant of a `menu` element whose `type` attribute in the list state	`menuitem` role
An element that defines a command, whose Type facet is "radio", and that is a descendant of a `menu` element whose `type` attribute in the list state	`menuitemradio` role, with the `aria-checked` state set to "true" if the command's Checked State facet is true, and "false" otherwise
Element that is disabled	The `aria-disabled` state set to "true"
Element with a `hidden` attribute	The `aria-hidden` state set to "true"
Element that is a candidate for constraint validation but that does not satisfy its constraints	The `aria-invalid` state set to "true"

Some HTML elements have native semantics that can be overridden. The following table lists these elements and their default implicit ARIA semantics, along with the restrictions that apply to those elements. Each language feature (element or attribute) in a cell in the first column implies, unless otherwise overridden, the ARIA semantic (role, state, or property) given in the cell in the second column of the same row, but this semantic may be overridden under the conditions listed in the cell in the third column of that row. In addition, any element may be given the presentation role, regardless of the restrictions below.

Language feature	Default implied ARIA semantic	Restrictions
`a` element that creates a hyperlink	`link` role	Role must be either `link`, `button`, `checkbox`, `menuitem`, `menuitemcheckbox`, `menuitemradio`, `tab`, or `treeitem`
`address` element	No role	If specified, role must be `contentinfo`
`article` element	`article` role	Role must be either `article`, `document`, `application`, or `main`
`aside` element	`note` role	Role must be either `note`, `complementary`, or `search`
`audio` element	No role	If specified, role must be `application`
`button` element	`button` role	Role must be either `button`, `link`, `menuitem`, `menuitemcheckbox`, `menuitemradio`, `radio`
`details` element	`group` role	Role must be a role that supports `aria-expanded`
`embed` element	No role	If specified, role must be either `application`, `document`, or `img`
`footer` element	No role	If specified, role must be `contentinfo`
`h1` element that does not have an `hgroup` ancestor	`heading` role, with the `aria-level` property set to the element's outline depth	Role must be either `heading` or `tab`
`h2` element that does not have an `hgroup` ancestor	`heading` role, with the `aria-level` property set to the element's outline depth	Role must be either `heading` or `tab`
`h3` element that does not have an `hgroup` ancestor	`heading` role, with the `aria-level` property set to the element's outline depth	Role must be either `heading` or `tab`
`h4` element that does not have an `hgroup` ancestor	`heading` role, with the `aria-level` property set to the element's outline depth	Role must be either `heading` or `tab`
`h5` element that does not have an `hgroup` ancestor	`heading` role, with the `aria-level` property set to the element's outline depth	Role must be either `heading` or `tab`
`h6` element that does not have an `hgroup` ancestor	`heading` role, with the `aria-level` property set to the element's outline depth	Role must be either `heading` or `tab`
`header` element	No role	If specified, role must be `banner`
`iframe` element	No role	If specified, role must be either `application`, `document`, or `img`
`img` element whose `alt` attribute's value is absent	`img` role	No restrictions
`img` element whose `alt` attribute's value is present and not empty	`img` role	No restrictions
`input` element with a `type` attribute in the Button state	`button` role	Role must be either `button`, `link`, `menuitem`, `menuitemcheckbox`, `menuitemradio`, `radio`
`input` element with a `type` attribute in the Checkbox state	`checkbox` role	Role must be either `checkbox` or `menuitemcheckbox`
`input` element with a `type` attribute in the Image Button state	`button` role	Role must be either `button`, `link`, `menuitem`, `menuitemcheckbox`, `menuitemradio`, `radio`
`input` element with a `type` attribute in the Radio Button state	`radio` role	Role must be either `radio` or `menuitemradio`
`li` element whose parent is an `ol` or `ul` element	`listitem` role	Role must be either `listitem`, `menuitemcheckbox`, `menuitemradio`, `option`, `tab`, or `treeitem`
`object` element	No role	If specified, role must be either `application`, `document`, or `img`
`ol` element	`list` role	Role must be either `directory`, `list`, `listbox`, `menu`, `menubar`, `tablist`, `toolbar`, `tree`
`output` element	`status` role	No restrictions
`section` element	`region` role	Role must be either `alert`, `alertdialog`, `application`, `contentinfo`, `dialog`, `document`, `log`, `main`, `marquee`, `region`, `search`, or `status`
`ul` element	`list` role	Role must be either `directory`, `list`, `listbox`, `menu`, `menubar`, `tablist`, `toolbar`, `tree`
`video` element	No role	If specified, role must be `application`
The body element	`document` role	Role must be either `document` or `application`

The entry "no role", when used as a strong native semantic, means that no role other than presentation can be used. When used as a default implied ARIA semantic, it means the user agent has no default mapping to ARIA roles. (However, it probably will have its own mappings to the accessibility layer.)

3.3 Dynamic markup insertion

APIs for dynamically inserting markup into the document interact with the parser, and thus their behavior varies depending on whether they are used with HTML documents (and the HTML parser) or XHTML in XML documents (and the XML parser).

3.3.1 Opening the input stream

The open() method comes in several variants with different numbers of arguments.

3.3.2 Closing the input stream

3.3.3 document.write()

3.3.4 document.writeln()

4 The elements of HTML

4.1 The root element

4.1.1 The html element

The manifest attribute only has an effect during the early stages of document load. Changing the attribute dynamically thus has no effect (and thus, no DOM API is provided for this attribute).

4.2 Document metadata

4.2.1 The head element

The title element is a required child in most situations, but when a higher-level protocol provides title information, e.g. in the Subject line of an e-mail when HTML is used as an e-mail authoring format, the title element can be omitted.

4.2.2 The title element

The title element represents the document's title or name. Authors should use titles that identify their documents even when they are used out of context, for example in a user's history or bookmarks, or in search results. The document's title is often different from its first heading, since the first heading does not have to stand alone when taken out of context.

The string to use as the document's title is given by the


document.title

IDL attribute.

4.2.3 The base element

A base element must have either an href attribute, a target attribute, or both.

A base element, if it has an href attribute, must come before any other elements in the tree that have attributes defined as taking URLs, except the html element (its manifest attribute isn't affected by base elements).

A base element, if it has a target attribute, must come before any elements in the tree that represent hyperlinks.

The href and target IDL attributes must reflect the respective content attributes of the same name.

4.2.4 The link element

Two categories of links can be created using the link element: Links to external resources and hyperlinks. The link types section defines whether a particular link type is an external resource or a hyperlink. One link element can create multiple links (of which some might be external resource links and some might be hyperlinks); exactly which and how many links are created depends on the keywords given in the rel attribute. User agents must process the links on a per-link basis, not a per-element basis.

Each link created for a link element is handled separately. For instance, if there are two link elements with rel="stylesheet", they each count as a separate external resource, and each is affected by its own attributes independently. Similarly, if a single link element has a rel attribute with the value

next
stylesheet

, it creates both a hyperlink (for the next keyword) and an external resource link (for the stylesheet keyword), and they are affected by other attributes (such as media or title) differently.

The exact behavior for links to external resources depends on the exact relationship, as defined for the relevant link type. Some of the attributes control whether or not the external resource is to be applied (as defined below).

Hyperlinks created with the link element and its rel attribute apply to the whole page. This contrasts with the rel attribute of a and area elements, which indicates the type of a link whose context is given by the link's location within the document.

The media attribute says which media the resource applies to. The value must be a valid media query.

The default, if the media attribute is omitted, is "all", meaning that by default links apply to all media.

The type attribute gives the MIME type of the linked resource. It is purely advisory. The value must be a valid MIME type.

For external resource links, the type attribute is used as a hint to user agents so that they can avoid fetching resources they do not support.

The title attribute gives the title of the link. With one exception, it is purely advisory. The value is text. The exception is for style sheet links, where the title attribute defines alternative style sheet sets.

The title attribute on link elements differs from the global title attribute of most other elements in that a link without a title does not inherit the title of the parent element: it merely has no title.

The sizes attribute is used with the icon link type. The attribute must not be specified on link elements that do not have a rel attribute that specifies the icon keyword.

The IDL attributes href, rel, media, hreflang, type, and sizes each must reflect the respective content attributes of the same name.

The IDL attribute disabled only applies to style sheet links. When the link element defines a style sheet link, then the disabled attribute behaves as defined for the alternative style sheets DOM. For all other link elements it always return false and does nothing on setting.

4.2.5 The meta element

The meta element can represent document-level metadata with the name attribute, pragma directives with the http-equiv attribute, and the file's character encoding declaration when an HTML document is serialized to string form (e.g. for transmission over the network or for disk storage) with the charset attribute.

If either name or http-equiv is specified, then the content attribute must also be specified. Otherwise, it must be omitted.

The charset attribute specifies the character encoding used by the document. This is a character encoding declaration. If the attribute is present in an XML document, its value must be an ASCII case-insensitive match for the string "UTF-8" (and the document is therefore forced to use UTF-8 as its encoding).

The charset attribute on the meta element has no effect in XML documents, and is only allowed in order to facilitate migration to and from XHTML.

There must not be more than one meta element with a charset attribute per document.

The content attribute gives the value of the document metadata or pragma directive when the element is used for those purposes. The allowed values depend on the exact context, as described in subsequent sections of this specification.

If a meta element has a name attribute, it sets document metadata. Document metadata is expressed in terms of name-value pairs, the name attribute on the meta element giving the name, and the content attribute on the same element giving the value. The name specifies what aspect of metadata is being set; valid names and the meaning of their values are described in the following sections. If a meta element has no content attribute, then the value part of the metadata name-value pair is the empty string.

The name and content IDL attributes must reflect the respective content attributes of the same name. The IDL attribute httpEquiv must reflect the content attribute http-equiv.

4.2.5.1 Standard metadata names

This specification defines a few names for the name attribute of the meta element.

4.2.5.2 Other metadata names

Anyone is free to edit the WHATWG Wiki MetaExtensions page at any time to add a type. These new names must be specified with the following information:

Metadata names whose values are to be URLs must not be proposed or accepted. Links must be represented using the link element, not the meta element.

4.2.5.3 Pragma directives

When the http-equiv attribute is specified on a meta element, the element is a pragma directive.

The http-equiv attribute is an enumerated attribute. The following table lists the keywords defined for this attribute. The states given in the first cell of the rows with keywords give the states to which those keywords map.

State	Keyword	Notes
Encoding declaration	`content-type`
Default style	`default-style`
Refresh	`refresh`

There must not be more than one meta element with any particular state in the document at a time.

4.2.5.4 Other pragma directives

Such extensions must use a name that is identical to an HTTP header registered in the Permanent Message Header Field Registry, and must have behavior identical to that described for the HTTP header. [IANAPERMHEADERS]

Pragma directives corresponding to headers describing metadata, or not requiring specific user agent processing, must not be registered; instead, use metadata names. Pragma directives corresponding to headers that affect the HTTP processing model (e.g. caching) must not be registered, as they would result in HTTP-level behavior being different for user agents that implement HTML than for user agents that do not.

Anyone is free to edit the WHATWG Wiki PragmaExtensions page at any time to add a pragma directive satisfying these conditions. Such registrations must specify the following information:

4.2.5.5 Specifying the document's character encoding

A character encoding declaration is a mechanism by which the character encoding used to store or transmit a document is specified.

In addition, due to a number of restrictions on meta elements, there can only be one meta-based character encoding declaration per document.

Authors are encouraged to use UTF-8. Conformance checkers may advise authors against using legacy encodings. [RFC3629]

Encodings in which a series of bytes in the range 0x20 to 0x7E can encode characters other than the corresponding characters in the range U+0020 to U+007E represent a potential security vulnerability: a user agent that does not support the encoding (or does not support the label used to declare the encoding, or does not use the same mechanism to detect the encoding of unlabelled content as another user agent) might end up interpreting technically benign plain text content as HTML tags and JavaScript. For example, this applies to encodings in which the bytes corresponding to "<script>" in ASCII can encode a different string. Authors should not use such encodings, which are known to include JIS_C6226-1983, JIS_X0212-1990, HZ-GB-2312, JOHAB (Windows code page 1361), encodings based on ISO-2022, and encodings based on EBCDIC. Furthermore, authors must not use the CESU-8, UTF-7, BOCU-1 and SCSU encodings, which also fall into this category, because these encodings were never intended for use for Web content. [RFC1345] [RFC1842] [RFC1468] [RFC2237] [RFC1554] [CP50220] [RFC1922] [RFC1557] [CESU8] [UTF7] [BOCU1] [SCSU]

Authors should not use UTF-32, as the encoding detection algorithms described in this specification intentionally do not distinguish it from UTF-16. [UNICODE]

Using non-UTF-8 encodings can have unexpected results on form submission and URL encodings, which use the document's character encoding by default.

In XHTML, the XML declaration should be used for inline character encoding information, if necessary.

4.2.6 The style element

The style element allows authors to embed style information in their documents. The style element is one of several inputs to the styling processing model. The element does not represent content for the user.

The type attribute gives the styling language. If the attribute is present, its value must be a valid MIME type that designates a styling language. The charset parameter must not be specified. The default value for the type attribute, which is used if the attribute is absent, is "text/css". [RFC2318]

The media attribute says which media the styles apply to. The value must be a valid media query.

The default, if the media attribute is omitted, is "all", meaning that by default styles apply to all media.

The scoped attribute is a boolean attribute. If present, it indicates that the styles are intended just for the subtree rooted at the style element's parent element, as opposed to the whole Document.

If the scoped attribute is present and the element has a parent element, then the style element must be the first node of flow content in its parent element other than inter-element whitespace, and the parent element's content model must not have a transparent component.

This implies that only one scoped style element is allowed at a time, and that such elements cannot be children of, e.g., a or ins elements, even when those are used as flow content containers.

The title attribute on style elements, like the title attribute on link elements, differs from the global title attribute in that a style block without a title does not inherit the title of the parent element: it merely has no title.

The


textContent

of a style element must match the style production in the following ABNF, the character set for which is Unicode. [ABNF]

This specification does not specify a style system, but CSS is expected to be supported by most Web browsers. [CSS]

The media, type and scoped IDL attributes must reflect the respective content attributes of the same name.

4.2.7 Styling

The link and style elements can provide styling information for the user agent to use when rendering the document. The CSS and CSSOM specifications specify what styling information is to be used by the user agent and how it is to be used. [CSS] [CSSOM]

4.3 Scripting

Authors are encouraged to use declarative alternatives to scripting where possible, as declarative mechanisms are often more maintainable, and many users disable scripting.

Authors are also encouraged to make their applications degrade gracefully in the absence of scripting support.

4.3.1 The script element

The script element allows authors to include dynamic script and data blocks in their documents. The element does not represent content for the user.

When used to include dynamic scripts, the scripts may either be embedded inline or may be imported from an external file using the src attribute. If the language is not that described by "text/javascript", then the type attribute must be present, as described below. Whatever language is used, the contents of the script element must conform with the requirements of that language's specification.

When used to include data blocks (as opposed to scripts), the data must be embedded inline, the format of the data must be given using the type attribute, the src attribute must not be specified, and the contents of the script element must conform to the requirements defined for the format used.

The type attribute gives the language of the script or format of the data. If the attribute is present, its value must be a valid MIME type. The charset parameter must not be specified. The default, which is used if the attribute is absent, is "text/javascript".

The src attribute, if specified, gives the address of the external script resource to use. The value of the attribute must be a valid non-empty URL potentially surrounded by spaces identifying a script resource of the type given by the type attribute, if the attribute is present, or of the type "text/javascript", if the attribute is absent. A resource is a script resource of a given type if that type identifies a scripting language and the resource conforms with the requirements of that language's specification.

The charset attribute gives the character encoding of the external script resource. The attribute must not be specified if the src attribute is not present. If the attribute is set, its value must be a valid character encoding name, must be an ASCII case-insensitive match for the preferred MIME name for that encoding, and must match the encoding given in the charset parameter of the Content-Type metadata of the external file, if any. [IANACHARSET]

The async and defer attributes are boolean attributes that indicate how the script should be executed. The defer and async attributes must not be specified if the src attribute is not present.

There are three possible modes that can be selected using these attributes. If the async attribute is present, then the script will be executed asynchronously, as soon as it is available. If the async attribute is not present but the defer attribute is present, then the script is executed when the page has finished parsing. If neither attribute is present, then the script is fetched and executed immediately, before the user agent continues parsing the page.

The exact processing details for these attributes are, for mostly historical reasons, somewhat non-trivial, involving a number of aspects of HTML. The implementation requirements are therefore by necessity scattered throughout the specification. The algorithms below (in this section) describe the core of this processing, but these algorithms reference and are referenced by the parsing rules for script start and end tags in HTML, in foreign content, and in XML, the rules for the document.write() method, the handling of scripting, etc.

The defer attribute may be specified even if the async attribute is specified, to cause legacy Web browsers that only support defer (and not async) to fall back to the defer behavior instead of the synchronous blocking behavior that is the default.

Changing the src, type, charset, async, and defer attributes dynamically has no direct effect; these attribute are only used at specific times described below.

The IDL attributes src, type, charset, and defer, each must reflect the respective content attributes of the same name.

The async IDL attribute controls whether the element will execute asynchronously or not. If the element's "force-async" flag is set, then, on getting, the async IDL attribute must return true, and on setting, the "force-async" flag must first be unset, and then the content attribute must be removed if the IDL attribute's new value is false, and must be set to the empty string if the IDL attribute's new value is true. If the element's "force-async" flag is not set, the IDL attribute must reflect the async content attribute.

When inserted using the document.write() method, script elements execute (typically synchronously), but when inserted using


innerHTML

and


outerHTML

attributes, they do not execute at all.

4.3.1.1 Scripting languages

The following lists some MIME type strings and the languages to which they refer:

4.3.1.2 Restrictions for contents of script elements

The


textContent

of a script element must match the script production in the following ABNF, the character set for which is Unicode. [ABNF]

When a script element contains script documentation, there are further restrictions on the contents of the element, as described in the section below.

4.3.1.3 Inline documentation for external scripts

If a script element's src attribute is specified, then the contents of the script element, if any, must be such that the value of the text IDL attribute, which is derived from the element's contents, matches the documentation production in the following ABNF, the character set for which is Unicode. [ABNF]

This requirement is in addition to the earlier restrictions on the syntax of contents of script elements.

4.3.2 The noscript element

The noscript element represents nothing if scripting is enabled, and represents its children if scripting is disabled. It is used to present different markup to user agents that support scripting and those that don't support scripting, by affecting how the document is parsed.

All these contortions are required because, for historical reasons, the noscript element is handled differently by the HTML parser based on whether scripting was enabled or not when the parser was invoked.

The noscript element is only effective in the HTML syntax, it has no effect in the XHTML syntax. This is because the way it works is by essentially "turning off" the parser when scripts are enabled, so that the contents of the element are treated as pure text and not as real elements. XML does not define a mechanism by which to do this.

4.4 Sections

4.4.1 The body element

In conforming documents, there is only one body element. The document.body IDL attribute provides scripts with easy access to a document's body element.

Thus, for example, a bubbling error event dispatched on a child of the body element of a Document would first trigger the onerror event handler content attributes of that element, then that of the root html element, and only then would it trigger the onerror event handler content attribute on the body element. This is because the event would bubble from the target, to the body, to the html, to the Document, to the Window, and the event handler on the body is watching the Window not the body. A regular event listener attached to the body using addEventListener(), however, would be run when the event bubbled through the body and not when it reaches the Window object.

4.4.2 The section element

The section element represents a generic section of a document or application. A section, in this context, is a thematic grouping of content, typically with a heading.

Examples of sections would be chapters, the various tabbed pages in a tabbed dialog box, or the numbered sections of a thesis. A Web site's home page could be split into sections for an introduction, news items, and contact information.

Authors are encouraged to use the article element instead of the section element when it would make sense to syndicate the contents of the element.

The section element is not a generic container element. When an element is needed only for styling purposes or as a convenience for scripting, authors are encouraged to use the div element instead. A general rule is that the section element is appropriate only if the element's contents would be listed explicitly in the document's outline.

4.4.3 The nav element

The nav element represents a section of a page that links to other pages or to parts within the page: a section with navigation links.

Not all groups of links on a page need to be in a nav element â€” the element is primarily intended for sections that consist of major navigation blocks. In particular, it is common for footers to have a short list of links to various pages of a site, such as the terms of service, the home page, and a copyright page. The footer element alone is sufficient for such cases; while a nav element can be used in such cases, it is usually unnecessary.

User agents (such as screen readers) that are targeted at users who can benefit from navigation information being omitted in the initial rendering, or who can benefit from navigation information being immediately available, can use this element as a way to determine what content on the page to initially skip and/or provide on request.

4.4.4 The article element

The article element represents a self-contained composition in a document, page, application, or site and that is, in principle, independently distributable or reusable, e.g. in syndication. This could be a forum post, a magazine or newspaper article, a blog entry, a user-submitted comment, an interactive widget or gadget, or any other independent item of content.

When article elements are nested, the inner article elements represent articles that are in principle related to the contents of the outer article. For instance, a blog entry on a site that accepts user-submitted comments could represent the comments as article elements nested within the article element for the blog entry.

Author information associated with an article element (q.v. the address element) does not apply to nested article elements.

When used specifically with content to be redistributed in syndication, the article element is similar in purpose to the entry element in Atom. [ATOM]

The schema.org microdata vocabulary can be used to provide the publication date for an article element, using one of the CreativeWork subtypes.

4.4.5 The aside element

The aside element represents a section of a page that consists of content that is tangentially related to the content around the aside element, and which could be considered separate from that content. Such sections are often represented as sidebars in printed typography.

The element can be used for typographical effects like pull quotes or sidebars, for advertising, for groups of nav elements, and for other content that is considered separate from the main content of the page.

It's not appropriate to use the aside element just for parentheticals, since those are part of the main flow of the document.

4.4.6 The h1, h2, h3, h4, h5, and h6 elements

The semantics and meaning of these elements are defined in the section on headings and sections.

These elements have a rank given by the number in their name. The h1 element is said to have the highest rank, the h6 element has the lowest rank, and two elements with the same name have equal rank.

4.4.7 The hgroup element

The hgroup element represents the heading of a section. The element is used to group a set of h1â€“h6 elements when the heading has multiple levels, such as subheadings, alternative titles, or taglines.

For the purposes of document summaries, outlines, and the like, the text of hgroup elements is defined to be the text of the highest ranked h1â€“h6 element descendant of the hgroup element, if there are any such elements, and the first such element if there are multiple elements with that rank. If there are no such elements, then the text of the hgroup element is the empty string.

Other elements of heading content in the hgroup element indicate subheadings or subtitles.

The rank of an hgroup element is the rank of the highest-ranked h1â€“h6 element descendant of the hgroup element, if there are any such elements, or otherwise the same as for an h1 element (the highest rank).

4.4.8 The header element

A header element is intended to usually contain the section's heading (an h1â€“h6 element or an hgroup element), but this is not required. The header element can also be used to wrap a section's table of contents, a search form, or any relevant logos.

4.4.9 The footer element

The footer element represents a footer for its nearest ancestor sectioning content or sectioning root element. A footer typically contains information about its section such as who wrote it, links to related documents, copyright data, and the like.

When the footer element contains entire sections, they represent appendices, indexes, long colophons, verbose license agreements, and other such content.

Contact information for the author or editor of a section belongs in an address element, possibly itself inside a footer.

Footers don't necessarily have to appear at the end of a section, though they usually do.

4.4.10 The address element

The address element represents the contact information for its nearest article or body element ancestor. If that is the body element, then the contact information applies to the document as a whole.

The address element must not be used to represent arbitrary addresses (e.g. postal addresses), unless those addresses are in fact the relevant contact information. (The p element is the appropriate element for marking up postal addresses in general.)

The address element must not contain information other than contact information.

Typically, the address element would be included along with other information in a footer element.

4.4.11 Headings and sections

The first element of heading content in an element of sectioning content represents the heading for that section. Subsequent headings of equal or higher rank start new (implied) sections, headings of lower rank start implied subsections that are part of the previous one. In both cases, the element represents the heading of the implied section.

Certain elements are said to be sectioning roots, including blockquote and td elements. These elements can have their own outlines, but the sections and headings inside these elements do not contribute to the outlines of their ancestors.

Sectioning content elements are always considered subsections of their nearest ancestor sectioning root or their nearest ancestor element of sectioning content, whichever is nearest, regardless of what implied sections other headings may have created.

Sections may contain headings of any rank, but authors are strongly encouraged to either use only h1 elements, or to use elements of the appropriate rank for the section's nesting level.

Authors are also encouraged to explicitly wrap sections in elements of sectioning content, instead of relying on the implicit sections generated by having multiple headings in one element of sectioning content.

4.4.11.1 Creating an outline

The outline for a sectioning content element or a sectioning root element consists of a list of one or more potentially nested sections. A section is a container that corresponds to some nodes in the original DOM tree. Each section can have one heading associated with it, and can contain any number of further nested sections. (The sections in the outline aren't section elements, though some may correspond to such elements â€” they are merely conceptual sections.)

4.5 Grouping content

4.5.1 The p element

While paragraphs are usually represented in visual media by blocks of text that are physically separated from adjacent blocks through blank lines, a style sheet or user agent would be equally justified in presenting paragraph breaks in a different manner, for instance using inline pilcrows (Â¶).

The p element should not be used when a more specific element is more appropriate.

4.5.2 The hr element

The hr element represents a paragraph-level thematic break, e.g. a scene change in a story, or a transition to another topic within a section of a reference book.

4.5.3 The pre element

The pre element represents a block of preformatted text, in which structure is represented by typographic conventions rather than by elements.

In the HTML syntax, a leading newline character immediately following the pre element start tag is stripped.

Authors are encouraged to consider how preformatted text will be experienced when the formatting is lost, as will be the case for users of speech synthesizers, braille displays, and the like. For cases like ASCII art, it is likely that an alternative presentation, such as a textual description, would be more universally accessible to the readers of the document.

To represent a block of computer code, the pre element can be used with a code element; to represent a block of computer output the pre element can be used with a samp element. Similarly, the kbd element can be used within a pre element to indicate text that the user is to enter.

4.5.4 The blockquote element

The blockquote element represents a section that is quoted from another source.

Content inside a blockquote must be quoted from another source, whose address, if it has one, may be cited in the cite attribute.

4.5.5 The ol element

The ol element represents a list of items, where the items have been intentionally ordered, such that changing the order would change the meaning of the document.

The items of the list are the li element child nodes of the ol element, in tree order.

The reversed attribute is a boolean attribute. If present, it indicates that the list is a descending list (..., 3, 2, 1). If the attribute is omitted, the list is an ascending list (1, 2, 3, ...).

The start attribute, if present, must be a valid integer giving the ordinal value of the first list item.

The type attribute can be used to specify the kind of marker to use in the list, in the cases where that matters (e.g. because items are to be referenced by their number/letter). The attribute, if specified, must have a value that is a case-sensitive match for one of the characters given in the first cell of one of the rows of the following table.

Keyword	State	Description	Examples for values 1-3 and 3999-4001
`1` (U+0031)	decimal	Decimal numbers	`1.`	`2.`	`3.`	...	`3999.`	`4000.`	`4001.`	...
`a` (U+0061)	lower-alpha	Lowercase latin alphabet	`a.`	`b.`	`c.`	...	`ewu.`	`ewv.`	`eww.`	...
`A` (U+0041)	upper-alpha	Uppercase latin alphabet	`A.`	`B.`	`C.`	...	`EWU.`	`EWV.`	`EWW.`	...
`i` (U+0069)	lower-roman	Lowercase roman numerals	`i.`	`ii.`	`iii.`	...	`mmmcmxcix.`	`iÌ…vÌ….`	`iÌ…vÌ…i.`	...
`I` (U+0049)	upper-roman	Uppercase roman numerals	`I.`	`II.`	`III.`	...	`MMMCMXCIX.`	`IÌ…VÌ….`	`IÌ…VÌ…I.`	...

The reversed, start, and type IDL attributes must reflect the respective content attributes of the same name. The start IDL attribute has the same default as its content attribute.

4.5.6 The ul element

The ul element represents a list of items, where the order of the items is not important â€” that is, where changing the order would not materially change the meaning of the document.

4.5.7 The li element

The li element represents a list item. If its parent element is an ol, ul, or menu element, then the element is an item of the parent element's list, as defined for those elements. Otherwise, the list item has no defined list-related relationship to any other li element.

If the parent element is an ol element, then the li element has an ordinal value.

The value IDL attribute must reflect the value of the value content attribute.

If the li element is the child of a menu element and itself has a child that defines a command, then the li element will match the


:enabled

and


:disabled

pseudo-classes in the same way as the first such child element does.

4.5.8 The dl element

The dl element represents an association list consisting of zero or more name-value groups (a description list). Each group must consist of one or more names (dt elements) followed by one or more values (dd elements). Within a single dl element, there should not be more than one dt element for each name.

Name-value groups may be terms and definitions, metadata topics and values, questions and answers, or any other groups of name-value data.

The values within a group are alternatives; multiple paragraphs forming part of the same value must all be given within the same dd element.

The order of the list of groups, and of the names and values within each group, may be significant.

4.5.9 The dt element

The dt element represents the term, or name, part of a term-description group in a description list (dl element).

The dt element itself, when used in a dl element, does not indicate that its contents are a term being defined, but this can be indicated using the dfn element.

4.5.10 The dd element

The dd element represents the description, definition, or value, part of a term-description group in a description list (dl element).

4.5.11 The figure element

The figure element represents some flow content, optionally with a caption, that is self-contained and is typically referenced as a single unit from the main flow of the document.

The element can thus be used to annotate illustrations, diagrams, photos, code listings, etc, that are referred to from the main content of the document, but that could, without affecting the flow of the document, be moved away from that primary content, e.g. to the side of the page, to dedicated pages, or to an appendix.

The figcaption element child of the element, if any, represents the caption of the figure element's contents. If there is no child figcaption element, then there is no caption.

4.5.12 The figcaption element

4.5.13 The div element

The div element has no special meaning at all. It represents its children. It can be used with the class, lang, and title attributes to mark up semantics common to a group of consecutive elements.

Authors are strongly encouraged to view the div element as an element of last resort, for when no other element is suitable. Use of more appropriate elements instead of the div element leads to better accessibility for readers and easier maintainability for authors.

4.6 Text-level semantics

4.6.1 The a element

If the a element has no href attribute, then the element represents a placeholder for where a link might otherwise have been placed, if it had been relevant.

The IDL attributes href, target, rel, media, hreflang, and type, must reflect the respective content attributes of the same name.

The a element also supports the complement of URL decomposition IDL attributes, protocol, host, port, hostname, pathname, search, and hash. These must follow the rules given for URL decomposition IDL attributes, with the input being the result of resolving the element's href attribute relative to the element, if there is such an attribute and resolving it is successful, or the empty string otherwise; and the common setter action being the same as setting the element's href attribute to the new output value.

4.6.2 The em element

The level of emphasis that a particular piece of content has is given by its number of ancestor em elements.

The placement of emphasis changes the meaning of the sentence. The element thus forms an integral part of the content. The precise way in which emphasis is used in this way depends on the language.

4.6.3 The strong element

The relative level of importance of a piece of content is given by its number of ancestor strong elements; each strong element increases the importance of its contents.

Changing the importance of a piece of text with the strong element does not change the meaning of the sentence.

4.6.4 The small element

Small print typically features disclaimers, caveats, legal restrictions, or copyrights. Small print is also sometimes used for attribution, or for satisfying licensing requirements.

The small element does not "de-emphasize" or lower the importance of text emphasized by the em element or marked as important with the strong element. To mark text as not emphasized or important, simply do not mark it up with the em or strong elements respectively.

The small element should not be used for extended spans of text, such as multiple paragraphs, lists, or sections of text. It is only intended for short runs of text. The text of a page listing terms of use, for instance, would not be a suitable candidate for the small element: in such a case, the text is not a side comment, it is the main content of the page.

4.6.5 The s element

The s element represents contents that are no longer accurate or no longer relevant.

The s element is not appropriate when indicating document edits; to mark a span of text as having been removed from a document, use the del element.

4.6.6 The cite element

The cite element represents the title of a work (e.g. a book, a paper, an essay, a poem, a score, a song, a script, a film, a TV show, a game, a sculpture, a painting, a theatre production, a play, an opera, a musical, an exhibition, a legal case report, etc). This can be a work that is being quoted or referenced in detail (i.e. a citation), or it can just be a work that is mentioned in passing.

A person's name is not the title of a work â€” even if people call that person a piece of work â€” and the element must therefore not be used to mark up people's names. (In some cases, the b element might be appropriate for names; e.g. in a gossip article where the names of famous people are keywords rendered with a different style to draw attention to them. In other cases, if an element is really needed, the span element can be used.)

4.6.7 The q element

Quotation punctuation (such as quotation marks) that is quoting the contents of the element must not appear immediately before, after, or inside q elements; they will be inserted into the rendering by the user agent.

Content inside a q element must be quoted from another source, whose address, if it has one, may be cited in the cite attribute. The source may be fictional, as when quoting characters in a novel or screenplay.

The q element must not be used in place of quotation marks that do not represent quotes; for example, it is inappropriate to use the q element for marking up sarcastic statements.

The use of q elements to mark up quotations is entirely optional; using explicit quotation punctuation without q elements is just as correct.

4.6.8 The dfn element

Defining term: If the dfn element has a title attribute, then the exact value of that attribute is the term being defined. Otherwise, if it contains exactly one element child node and no child text nodes, and that child element is an abbr element with a title attribute, then the exact value of that attribute is the term being defined. Otherwise, it is the exact


textContent

of the dfn element that gives the term being defined.

If the title attribute of the dfn element is present, then it must contain only the term being defined.

An a element that links to a dfn element represents an instance of the term defined by the dfn element.

4.6.9 The abbr element

The abbr element represents an abbreviation or acronym, optionally with its expansion. The title attribute may be used to provide an expansion of the abbreviation. The attribute, if specified, must contain an expansion of the abbreviation, and nothing else.

If an abbreviation is pluralized, the expansion's grammatical number (plural vs singular) must match the grammatical number of the contents of the element.

Abbreviations do not have to be marked up using this element. It is expected to be useful in the following cases:

Providing an expansion in a title attribute once will not necessarily cause other abbr elements in the same document with the same contents but without a title attribute to behave as if they had the same expansion. Every abbr element is independent.

4.6.10 The time element

The time element represents its contents, along with a machine-readable form of those contents in the datetime attribute. The kind of content is limited to various kinds of dates, times, time-zone offsets, and durations, as described below.

The datetime attribute may be present. If present, its value must be a representation of the element's contents in a machine-readable format.

A time element that does not have a datetime content attribute must not have any element descendants.

The datetime value of a time element is the value of the element's datetime content attribute, if it has one, or the element's


textContent

, if it does not.

The datetime value of a time element must match one of the following syntaxes.

The datetime IDL attribute must reflect the content attribute of the same name.

4.6.11 The code element

The code element represents a fragment of computer code. This could be an XML element name, a filename, a computer program, or any other string that a computer would recognize.

Although there is no formal way to indicate the language of computer code being marked up, authors who wish to mark code elements with the language used, e.g. so that syntax highlighting scripts can use the right rules, may do so by adding a class prefixed with "language-" to the element.

4.6.12 The var element

The var element represents a variable. This could be an actual variable in a mathematical expression or programming context, an identifier representing a constant, a function parameter, or just be a term used as a placeholder in prose.

For mathematics, in particular for anything beyond the simplest of expressions, MathML is more appropriate. However, the var element can still be used to refer to specific variables that are then mentioned in MathML expressions.

4.6.13 The samp element

The samp element represents (sample) output from a program or computing system.

4.6.14 The kbd element

The kbd element represents user input (typically keyboard input, although it may also be used to represent other input, such as voice commands).

When the kbd element is nested inside a samp element, it represents the input as it was echoed by the system.

When the kbd element contains a samp element, it represents input based on system output, for example invoking a menu item.

When the kbd element is nested inside another kbd element, it represents an actual key or other single unit of input as appropriate for the input mechanism.

4.6.15 The sub and sup elements

These elements must be used only to mark up typographical conventions with specific meanings, not for typographical presentation for presentation's sake. For example, it would be inappropriate for the sub and sup elements to be used in the name of the LaTeX document preparation system. In general, authors should use these elements only if the absence of those elements would change the meaning of the content.

In certain languages, superscripts are part of the typographical conventions for some abbreviations.

The sub element can be used inside a var element, for variables that have subscripts.

Mathematical expressions often use subscripts and superscripts. Authors are encouraged to use MathML for marking up mathematics, but authors may opt to use sub and sup if detailed mathematical markup is not desired. [MATHML]

4.6.16 The i element

The i element represents a span of text in an alternate voice or mood, or otherwise offset from the normal prose in a manner indicating a different quality of text, such as a taxonomic designation, a technical term, an idiomatic phrase from another language, a thought, or a ship name in Western texts.

Authors can use the class attribute on the i element to identify why the element is being used, so that if the style of a particular use (e.g. dream sequences as opposed to taxonomic terms) is to be changed at a later date, the author doesn't have to go through the entire document (or series of related documents) annotating each use.

Authors are encouraged to consider whether other elements might be more applicable than the i element, for instance the em element for marking up stress emphasis, or the dfn element to mark up the defining instance of a term.

Style sheets can be used to format i elements, just like any other element can be restyled. Thus, it is not the case that content in i elements will necessarily be italicized.

4.6.17 The b element

The b element represents a span of text to which attention is being drawn for utilitarian purposes without conveying any extra importance and with no implication of an alternate voice or mood, such as key words in a document abstract, product names in a review, actionable words in interactive text-driven software, or an article lede.

As with the i element, authors can use the class attribute on the b element to identify why the element is being used, so that if the style of a particular use is to be changed at a later date, the author doesn't have to go through annotating each use.

The b element should be used as a last resort when no other element is more appropriate. In particular, headings should use the h1 to h6 elements, stress emphasis should use the em element, importance should be denoted with the strong element, and text marked or highlighted should use the mark element.

Style sheets can be used to format b elements, just like any other element can be restyled. Thus, it is not the case that content in b elements will necessarily be boldened.

4.6.18 The u element

The u element represents a span of text with an unarticulated, though explicitly rendered, non-textual annotation, such as labeling the text as being a proper name in Chinese text (a Chinese proper name mark), or labeling the text as being misspelt.

In most cases, another element is likely to be more appropriate: for marking stress emphasis, the em element should be used; for marking key words or phrases either the b element or the mark element should be used, depending on the context; for marking book titles, the cite element should be used; for labeling text with explicit textual annotations, the ruby element should be used; for labeling ship names in Western texts, the i element should be used.

The default rendering of the u element in visual presentations clashes with the conventional rendering of hyperlinks (underlining). Authors are encouraged to avoid using the u element where it could be confused for a hyperlink.

4.6.19 The mark element

The mark element represents a run of text in one document marked or highlighted for reference purposes, due to its relevance in another context. When used in a quotation or other block of text referred to from the prose, it indicates a highlight that was not originally present but which has been added to bring the reader's attention to a part of the text that might not have been considered important by the original author when the block was originally written, but which is now under previously unexpected scrutiny. When used in the main prose of a document, it indicates a part of the document that has been highlighted due to its likely relevance to the user's current activity.

4.6.20 The ruby element

The ruby element allows one or more spans of phrasing content to be marked with ruby annotations. Ruby annotations are short runs of text presented alongside base text, primarily used in East Asian typography as a guide for pronunciation or to include other annotations. In Japanese, this form of typography is also known as furigana.

A ruby element represents the spans of phrasing content it contains, ignoring all the child rt and rp elements and their descendants. Those spans of phrasing content have associated annotations created using the rt element.

4.6.21 The rt element

An rt element represents an annotation (given by its children) for the zero or more nodes of phrasing content that immediately precedes it in the ruby element, ignoring rp elements.

4.6.22 The rp element

The rp element can be used to provide parentheses around a ruby text component of a ruby annotation, to be shown by user agents that don't support ruby annotations.

4.6.23 The bdi element

The bdi element represents a span of text that is to be isolated from its surroundings for the purposes of bidirectional text formatting. [BIDI]

The dir global attribute defaults to auto on this element (it never inherits from the parent element like with other elements).

4.6.24 The bdo element

The bdo element represents explicit text directionality formatting control for its children. It allows authors to override the Unicode bidirectional algorithm by explicitly specifying a direction override. [BIDI]

Authors must specify the dir attribute on this element, with the value ltr to specify a left-to-right override and with the value rtl to specify a right-to-left override.

4.6.25 The span element

The span element doesn't mean anything on its own, but can be useful when used together with the global attributes, e.g. class, lang, or dir. It represents its children.

4.6.26 The br element

While line breaks are usually represented in visual media by physically moving subsequent text to a new line, a style sheet or user agent would be equally justified in causing line breaks to be rendered in a different manner, for instance as green dots, or as extra spacing.

br elements must be used only for line breaks that are actually part of the content, as in poems or addresses.

If a paragraph consists of nothing but a single br element, it represents a placeholder blank line (e.g. as in a template). Such blank lines must not be used for presentation purposes.

4.6.27 The wbr element

4.6.28 Usage summary

Element	Purpose	Example
`a`	Hyperlinks	Visit my <a href="drinks.html">drinks</a> page.
`em`	Stress emphasis	I must say I <em>adore</em> lemonade.
`strong`	Importance	This tea is <strong>very hot</strong>.
`small`	Side comments	These grapes are made into wine. <small>Alcohol is addictive.</small>
`s`	Inaccurate text	Price: <s>Â£4.50</s> Â£2.00!
`cite`	Titles of works	The case <cite>Hugo v. Danielle</cite> is relevant here.
`q`	Quotations	The judge said <q>You can drink water from the fish tank</q> but advised against it.
`dfn`	Defining instance	The term <dfn>organic food</dfn> refers to food produced without synthetic chemicals.
`abbr`	Abbreviations	Organic food in Ireland is certified by the <abbr title="Irish Organic Farmers and Growers Association">IOFGA</abbr>.
`time`	Machine-readable equivalent of date- or time-related data	Available starting on <time datetime="2011-11-12">November 12th</time>!
`code`	Computer code	The <code>fruitdb</code> program can be used for tracking fruit production.
`var`	Variables	If there are <var>n</var> fruit in the bowl, at least <var>n</var>Ã·2 will be ripe.
`samp`	Computer output	The computer said <samp>Unknown error -3</samp>.
`kbd`	User input	Hit <kbd>F1</kbd> to continue.
`sub`	Subscripts	Water is H<sub>2</sub>O.
`sup`	Superscripts	The Hydrogen in heavy water is usually <sup>2</sup>H.
`i`	Alternative voice	Lemonade consists primarily of <i>Citrus limon</i>.
`b`	Keywords	Take a <b>lemon</b> and squeeze it with a <b>juicer</b>.
`u`	Annotations	The mixture of apple juice and <u class="spelling">eldeflower</u> juice is very pleasant.
`mark`	Highlight	Elderflower cordial, with one <mark>part</mark> cordial to ten <mark>part</mark>s water, stands a<mark>part</mark> from the rest.
`ruby`, `rt`, `rp`	Ruby annotations	<ruby> OJ <rp>(<rt>Orange Juice<rp>)</ruby>
`bdi`	Text directionality isolation	The recommended restaurant is <bdi lang="">My Juice CafÃ© (At The Beach)</bdi>.
`bdo`	Text directionality formatting	The proposal is to write English, but in reverse order. "Juice" would become "<bdo dir=rtl>Juice</bdo>"
`span`	Other	In French we call it <span lang="fr">sirop de sureau</span>.
`br`	Line break	Simply Orange Juice Company<br>Apopka, FL 32703<br>U.S.A.
`wbr`	Line breaking opportunity	www.simply<wbr>orange<wbr>juice.com

4.7 Edits

4.7.1 The ins element

4.7.2 The del element

4.7.3 Attributes common to ins and del elements

The cite attribute may be used to specify the address of a document that explains the change. When that document is long, for instance the minutes of a meeting, authors are encouraged to include a fragment identifier pointing to the specific part of that document that discusses the change.

The datetime attribute may be used to specify the time and date of the change.

The cite IDL attribute must reflect the element's cite content attribute. The dateTime IDL attribute must reflect the element's datetime content attribute.

4.7.4 Edits and paragraphs

Since the ins and del elements do not affect paragraphing, it is possible, in some cases where paragraphs are implied (without explicit p elements), for an ins or del element to span both an entire paragraph or other non-phrasing content elements and part of another paragraph. For example:

By only wrapping some paragraphs in p elements, one can even get the end of one paragraph, a whole second paragraph, and the start of a third paragraph to be covered by the same ins or del element (though this is very confusing, and not considered good practice):

However, due to the way implied paragraphs are defined, it is not possible to mark up the end of one paragraph and the start of the very next one using the same ins or del element. You instead have to use one (or two) p element(s) and two ins or del elements, as for example:

Partly because of the confusion described above, authors are strongly encouraged to always mark up all paragraphs with the p element, instead of having ins or del elements that cross implied paragraphs boundaries.

4.7.5 Edits and lists

The content models of the ol and ul elements do not allow ins and del elements as children. Lists always represent all their items, including items that would otherwise have been marked as deleted.

To indicate that an item is inserted or deleted, an ins or del element can be wrapped around the contents of the li element. To indicate that an item has been replaced by another, a single li element can have one or more del elements followed by one or more ins elements.

4.7.6 Edits and tables

The elements that form part of the table model have complicated content model requirements that do not allow for the ins and del elements, so indicating edits to a table can be difficult.

To indicate that an entire row or an entire column has been added or removed, the entire contents of each cell in that row or column can be wrapped in ins or del elements (respectively).

Generally speaking, there is no good way to indicate more complicated edits (e.g. that a cell was removed, moving all subsequent cells up or to the left).

4.8 Embedded content

4.8.1 The img element

The image given by the src attribute is the embedded content; the value of the alt attribute provides equivalent content for those who cannot process images or who have image loading disabled.

Images can thus be static bitmaps (e.g. PNGs, GIFs, JPEGs), single-page vector documents (single-page PDFs, XML files with an SVG root element), animated bitmaps (APNGs, animated GIFs), animated vector graphics (XML files with an SVG root element that use declarative SMIL animation), and so forth. However, this also precludes SVG files with script, multipage PDF files, interactive MNG files, HTML documents, plain text documents, and so forth.

The img element must not be used as a layout tool. In particular, img elements should not be used to display transparent images, as they rarely convey meaning and rarely add anything useful to the document.

The crossorigin attribute is a CORS settings attribute. Its purpose is to allow images from third-party sites that allow cross-origin access to be used with canvas.

The usemap attribute, if present, can indicate that the image has an associated image map.

The ismap attribute, when used on an element that is a descendant of an a element with an href attribute, indicates by its presence that the element provides access to a server-side image map. This affects how events are handled on the corresponding a element.

The ismap attribute is a boolean attribute. The attribute must not be specified on an element that does not have an ancestor a element with an href attribute.

The alt and src IDL attributes must reflect the respective content attributes of the same name.

The crossOrigin IDL attribute must reflect the crossorigin content attribute.

On setting, they must act as if they reflected the respective content attributes of the same name.

Three constructors are provided for creating HTMLImageElement objects (in addition to the factory methods from DOM Core such as createElement()): Image(), Image(width), and Image(width, height). When invoked as constructors, these must return a new HTMLImageElement object (a new img element). If the width argument is present, the new object's width content attribute must be set to width. If the height argument is also present, the new object's height content attribute must be set to height. The element's document must be the active document of the browsing context of the Window object on which the interface object of the invoked constructor is found.

4.8.1.1 Requirements for providing text to act as an alternative for images

4.8.1.1.1 General guidelines

Except where otherwise specified, the alt attribute must be specified and its value must not be empty; the value must be an appropriate replacement for the image. The specific requirements for the alt attribute depend on what the image is intended to represent, as described in the following sections.

The most general rule to consider when writing alternative text is the following: the intent is that replacing every image with the text of its alt attribute not change the meaning of the page.

So, in general, alternative text can be written by considering what one would have written had one not been able to include the image.

A corollary to this is that the alt attribute's value should never contain text that could be considered the image's caption, title, or legend. It is supposed to contain replacement text that could be used by users instead of the image; it is not meant to supplement the image. The title attribute can be used for supplemental information.

One way to think of alternative text is to think about how you would read the page containing the image to someone over the phone, without mentioning that there is an image present. Whatever you say instead of the image is typically a good start for writing the alternative text.

4.8.1.1.2 A link or button containing nothing but the image

When an a element that creates a hyperlink, or a button element, has no textual content but contains one or more images, the alt attributes must contain text that together convey the purpose of the link or button.

4.8.1.1.3 A phrase or paragraph with an alternative graphical representation: charts, diagrams, graphs, maps, illustrations

Sometimes something can be more clearly stated in graphical form, for example as a flowchart, a diagram, a graph, or a simple map showing directions. In such cases, an image can be given using the img element, but the lesser textual version must still be given, so that users who are unable to view the image (e.g. because they have a very slow connection, or because they are using a text-only browser, or because they are listening to the page being read out by a hands-free automobile voice Web browser, or simply because they are blind) are still able to understand the message being conveyed.

The text must be given in the alt attribute, and must convey the same message as the image specified in the src attribute.

It is important to realize that the alternative text is a replacement for the image, not a description of the image.

4.8.1.1.4 A short phrase or label with an alternative graphical representation: icons, logos

A document can contain information in iconic form. The icon is intended to help users of visual browsers to recognize features at a glance.

In some cases, the icon is supplemental to a text label conveying the same meaning. In those cases, the alt attribute must be present but must be empty.

In other cases, the icon has no text next to it describing what it means; the icon is supposed to be self-explanatory. In those cases, an equivalent textual label must be given in the alt attribute.

Many pages include logos, insignia, flags, or emblems, which stand for a particular entity such as a company, organization, project, band, software package, country, or some such.

If the logo is being used to represent the entity, e.g. as a page heading, the alt attribute must contain the name of the entity being represented by the logo. The alt attribute must not contain text like the word "logo", as it is not the fact that it is a logo that is being conveyed, it's the entity itself.

If the logo is being used next to the name of the entity that it represents, then the logo is supplemental, and its alt attribute must instead be empty.

If the logo is merely used as decorative material (as branding, or, for example, as a side image in an article that mentions the entity to which the logo belongs), then the entry below on purely decorative images applies. If the logo is actually being discussed, then it is being used as a phrase or paragraph (the description of the logo) with an alternative graphical representation (the logo itself), and the first entry above applies.

4.8.1.1.5 Text that has been rendered to a graphic for typographical effect

Sometimes, an image just consists of text, and the purpose of the image is not to highlight the actual typographic effects used to render the text, but just to convey the text itself.

In such cases, the alt attribute must be present but must consist of the same text as written in the image itself.

4.8.1.1.6 A graphical representation of some of the surrounding text

In many cases, the image is actually just supplementary, and its presence merely reinforces the surrounding text. In these cases, the alt attribute must be present but its value must be the empty string.

In general, an image falls into this category if removing the image doesn't make the page any less useful, but including the image makes it a lot easier for users of visual browsers to understand the concept.

4.8.1.1.7 A purely decorative image that doesn't add any information

If an image is decorative but isn't especially page-specific â€” for example an image that forms part of a site-wide design scheme â€” the image should be specified in the site's CSS, not in the markup of the document.

Exceptions to this rule, in cases where CSS cannot be used to display an entirely decorative image, are covered by the HTML5: Techniques for providing useful text alternatives. [HTMLALTTECHS] Authors are also encouraged to consult the Web Content Accessibility Guidelines 2.0 for more detailed information and acceptable techniques. [WCAG]

4.8.1.1.8 A group of images that form a single larger picture with no links

When a picture has been sliced into smaller image files that are then displayed together to form the complete picture again, one of the images must have its alt attribute set as per the relevant rules that would be appropriate for the picture as a whole, and then all the remaining images must have their alt attribute set to the empty string.

4.8.1.1.9 A group of images that form a single larger picture with links

However, if an image is indeed sliced and any of the components of the sliced picture are the sole contents of links, then one image per link must have alternative text in its alt attribute representing the purpose of the link.

4.8.1.1.10 A key part of the content

In some cases, the image is a critical part of the content. This could be the case, for instance, on a page that is part of a photo gallery. The image is the whole point of the page containing it.

How to provide alternative text for an image that is a key part of the content depends on the image's provenance.

4.8.1.1.11 An image not intended for the user

Generally authors should avoid using img elements for purposes other than showing images.

If an img element is being used for purposes other than showing an image, e.g. as part of a service to count page views, then the alt attribute must be the empty string.

4.8.2 The iframe element

The srcdoc attribute gives the content of the page that the nested browsing context is to contain. The value of the attribute is the source of an iframe srcdoc document.

For iframe elements in HTML documents, the attribute, if present, must have a value using the HTML syntax that consists of the following syntactic components, in the given order:

For iframe elements in XML documents, the attribute, if present, must have a value that matches the production labeled document in the XML specification. [XML]

If the src attribute and the srcdoc attribute are both specified together, the srcdoc attribute takes priority. This allows authors to provide a fallback URL for legacy user agents that do not support the srcdoc attribute.

If, when the element is created, the srcdoc attribute is not set, and the src attribute is either also not set or set but its value cannot be resolved, the browsing context will remain at the initial


about:blank

page.

If the user navigates away from this page, the iframe's corresponding


WindowProxy

object will proxy new Window objects for new Document objects, but the src attribute will not change.

In the HTML syntax, authors need only remember to use U+0022 QUOTATION MARK characters (") to wrap the attribute contents and then to escape all U+0022 QUOTATION MARK (") and U+0026 AMPERSAND (&) characters, and to specify the sandbox attribute, to ensure safe embedding of content.

Due to restrictions of the XHTML syntax, in XML the U+003C LESS-THAN SIGN character (<) needs to be escaped as well. In order to prevent attribute-value normalization, some of XML's whitespace characters â€” specifically U+0009 CHARACTER TABULATION (tab), U+000A LINE FEED (LF), and U+000D CARRIAGE RETURN (CR) â€” also need to be escaped. [XML]

Setting both the


allow-scripts

and


allow-same-origin

keywords together when the embedded page has the same origin as the page containing the iframe allows the embedded page to simply remove the sandbox attribute.

Sandboxing hostile content is of minimal help if an attacker can convince the user to just visit the hostile content directly, rather than in the iframe. To limit the damage that can be caused by hostile HTML content, it should be served from a separate dedicated domain.

Potentially hostile files should not be served from the same server as the file containing the iframe element. Using a different domain ensures that scripts in the files are unable to attack the site, even if the user is tricked into visiting those pages directly, without the protection of the sandbox attribute.

If the


allow-scripts

keyword is set along with


allow-same-origin

keyword, and the file is from the same origin as the iframe's Document, then a script in the "sandboxed" iframe could just reach out, remove the sandbox attribute, and then reload itself, effectively breaking out of the sandbox altogether.

The seamless attribute is a boolean attribute. When specified, it indicates that the iframe element's browsing context is to be rendered in a manner that makes it appear to be part of the containing document (seamlessly included in the parent document).

The attribute can be set or removed dynamically, with the rendering updating in tandem.

The iframe element supports dimension attributes for cases where the embedded content has specific dimensions (e.g. ad units have well-defined dimensions).

An iframe element never has fallback content, as it will always create a nested browsing context, regardless of whether the specified initial contents are successfully used.

Descendants of iframe elements represent nothing. (In legacy user agents that do not support iframe elements, the contents would be parsed as markup that could act as fallback content.)

When used in HTML documents, the allowed content model of iframe elements is text, except that invoking the HTML fragment parsing algorithm with the iframe element as the context element and the text contents as the input must result in a list of nodes that are all phrasing content, with no parse errors having occurred, with no script elements being anywhere in the list or as descendants of elements in the list, and with all the elements in the list (including their descendants) being themselves conforming.

The IDL attributes src, srcdoc, name, sandbox, and seamless must reflect the respective content attributes of the same name.

4.8.3 The embed element

The embed element represents an integration point for an external (typically non-HTML) application or interactive content.

The type attribute, if present, gives the MIME type by which the plugin to instantiate is selected. The value must be a valid MIME type. If both the type attribute and the src attribute are present, then the type attribute must specify the same type as the explicit Content-Type metadata of the resource given by the src attribute.

Any namespace-less attribute other than name, align, hspace, and vspace may be specified on the embed element, so long as its name is XML-compatible and contains no characters in the range U+0041 to U+005A (LATIN CAPITAL LETTER A to LATIN CAPITAL LETTER Z). These attributes are then passed as parameters to the plugin.

All attributes in HTML documents get lowercased automatically, so the restriction on uppercase letters doesn't affect such documents.

The four exceptions are to exclude legacy attributes that have side-effects beyond just sending parameters to the plugin.

The IDL attributes src and type each must reflect the respective content attributes of the same name.

4.8.4 The object element

The object element can represent an external resource, which, depending on the type of the resource, will either be treated as an image, as a nested browsing context, or as an external resource to be processed by a plugin.

Authors who reference resources from other origins that they do not trust are urged to use the typemustmatch attribute defined below. Without that attribute, it is possible in certain cases for an attacker on the remote host to use the plugin mechanism to run arbitrary scripts, even if the author has used features such as the Flash "allowScriptAccess" parameter.

The type attribute, if present, specifies the type of the resource. If present, the attribute must be a valid MIME type.

At least one of either the data attribute or the type attribute must be present.

The typemustmatch attribute is a boolean attribute whose presence indicates that the resource specified by the data attribute is only to be used if the value of the type attribute and the Content-Type of the aforementioned resource match.

The typemustmatch attribute must not be specified unless both the data attribute and the type attribute are present.

The usemap attribute, if present while the object element represents an image, can indicate that the object has an associated image map.

The form attribute is used to explicitly associate the object element with its form owner.

The IDL attributes data, type and name each must reflect the respective content attributes of the same name. The typeMustMatch IDL attribute must reflect the typemustmatch content attribute. The useMap IDL attribute must reflect the usemap content attribute.

The contentWindow IDL attribute must return the


WindowProxy

object of the object element's nested browsing context, if it has one; otherwise, it must return null.

4.8.5 The param element

The param element defines parameters for plugins invoked by object elements. It does not represent anything on its own.

The IDL attributes name and value must both reflect the respective content attributes of the same name.

4.8.6 The video element

A video element is used for playing videos or movies, and audio files with captions.

Content may be provided inside the video element; it is intended for older Web browsers which do not support video, so that legacy video plugins can be tried, or to show text to the users of these older browsers informing them of how to access the video contents.

In particular, this content is not intended to address accessibility concerns. To make video content accessible to the blind, deaf, and those with other physical or cognitive disabilities, a variety of features are available. Captions can be provided, either embedded in the video stream or as external files using the track element. Sign-language tracks can be provided, again either embedded in the video stream or by synchronizing multiple video elements using the mediagroup attribute or a MediaController object. Audio descriptions can be provided, either as a separate track embedded in the video stream, or a separate audio track in an audio element slaved to the same controller as the video element(s), or in text form using a WebVTT file referenced using the track element and synthesized into speech by the user agent. WebVTT can also be used to provide chapter titles. For users who would rather not use a media element at all, transcripts or other textual alternatives can be provided by simply linking to them in the prose near the video element. [WEBVTT]

The video element is a media element whose media data is ostensibly video data, possibly with associated audio data.

The poster attribute gives the address of an image file that the user agent can show while no video data is available. The attribute, if present, must contain a valid non-empty URL potentially surrounded by spaces.

The image given by the poster attribute, the poster frame, is intended to be a representative frame of the video (typically one of the first non-blank frames) that gives the user an idea of what the video is like.

4.8.7 The audio element

Content may be provided inside the audio element; it is intended for older Web browsers which do not support audio, so that legacy audio plugins can be tried, or to show text to the users of these older browsers informing them of how to access the audio contents.

In particular, this content is not intended to address accessibility concerns. To make audio content accessible to the deaf or to those with other physical or cognitive disabilities, a variety of features are available. If captions or a sign language video are available, the video element can be used instead of the audio element to play the audio, allowing users to enable the visual alternatives. Chapter titles can be provided to aid navigation, using the track element and a WebVTT file. And, naturally, transcripts or other textual alternatives can be provided by simply linking to them in the prose near the audio element. [WEBVTT]

4.8.8 The source element

Dynamically modifying a source element and its attribute when the element is already inserted in a video or audio element will have no effect. To change what is playing, just use the src attribute on the media element directly, possibly making use of the canPlayType() method to pick from amongst available resources. Generally, manipulating source elements manually after the document has been parsed is an unncessarily complicated approach.

The type attribute gives the type of the media resource, to help the user agent determine if it can play this media resource before fetching it. If specified, its value must be a valid MIME type. The codecs parameter, which certain MIME types define, might be necessary to specify exactly how the resource is encoded. [RFC4281]

The media attribute gives the intended media type of the media resource, to help the user agent determine if this media resource is useful to the user before fetching it. Its value must be a valid media query.

The default, if the media attribute is omitted, is "all", meaning that by default the media resource is suitable for all media.

The IDL attributes src, type, and media must reflect the respective content attributes of the same name.

4.8.9 The track element

The kind attribute is an enumerated attribute. The following table lists the keywords defined for this attribute. The keyword given in the first cell of each row maps to the state given in the second cell.

Keyword	State	Brief description
`subtitles`	Subtitles	Transcription or translation of the dialogue, suitable for when the sound is available but not understood (e.g. because the user does not understand the language of the media resource's audio track). Overlaid on the video.
`captions`	Captions	Transcription or translation of the dialogue, sound effects, relevant musical cues, and other relevant audio information, suitable for when sound is unavailable or not clearly audible (e.g. because it is muted, drowned-out by ambient noise, or because the user is deaf). Overlaid on the video; labeled as appropriate for the hard-of-hearing.
`descriptions`	Descriptions	Textual descriptions of the video component of the media resource, intended for audio synthesis when the visual component is obscured, unavailable, or not usable (e.g. because the user is interacting with the application without a screen while driving, or because the user is blind). Synthesized as audio.
`chapters`	Chapters	Chapter titles, intended to be used for navigating the media resource. Displayed as an interactive (potentially nested) list in the user agent's interface.
`metadata`	Metadata	Tracks intended for use from script. Not displayed by the user agent.

The attribute may be omitted. The missing value default is the subtitles state.

The srclang attribute gives the language of the text track data. The value must be a valid BCP 47 language tag. This attribute must be present if the element's kind attribute is in the subtitles state. [BCP47]

The label attribute gives a user-readable title for the track. This title is used by user agents when listing subtitle, caption, and audio description tracks in their user interface.

The value of the label attribute, if the attribute is present, must not be the empty string. Furthermore, there must not be two track element children of the same media element whose kind attributes are in the same state, whose srclang attributes are both missing or have values that represent the same language, and whose label attributes are again both missing or both have the same value.

The default attribute, if specified, indicates that the track is to be enabled if the user's preferences do not indicate that another track would be more appropriate. There must not be more than one track element with the same parent node with the default attribute specified.

The src, srclang, label, and default IDL attributes must reflect the respective content attributes of the same name. The kind IDL attribute must reflect the content attribute of the same name, limited to only known values.

4.8.10 Media elements

Media elements (audio and video, in this specification) implement the following interface:

Media elements are used to present audio data, or video and audio data, to the user. This is referred to as media data in this section, since this section applies equally to media elements for audio or for video. The term media resource is used to refer to the complete set of media data, e.g. the complete video file, or complete audio file.

A media resource can have multiple audio and video tracks. For the purposes of a media element, the video data of the media resource is only that of the currently selected track (if any) given by the element's videoTracks attribute, and the audio data of the media resource is the result of mixing all the currently enabled tracks (if any) given by the element's audioTracks attribute.

Both audio and video elements can be used for both audio and video. The main difference between the two is simply that the audio element has no playback area for visual content (such as video or captions), whereas the video element does.

4.8.10.1 Error codes

4.8.10.2 Location of the media resource

The src IDL attribute on media elements must reflect the content attribute of the same name.

The crossOrigin IDL attribute must reflect the crossorigin content attribute.

There are two ways to specify a media resource, the src attribute, or source elements. The attribute overrides the elements.

4.8.10.3 MIME types

A media resource can be described in terms of its type, specifically a MIME type, in some cases with a codecs parameter. (Whether the codecs parameter is allowed or not depends on the MIME type.) [RFC4281]

Types are usually somewhat incomplete descriptions; for example "video/mpeg" doesn't say anything except what the container type is, and even a type like "video/mp4; codecs="avc1.42E01E, mp4a.40.2"" doesn't include information like the actual bitrate (only the maximum bitrate). Thus, given a type, a user agent can often only know whether it might be able to play media of that type (with varying levels of confidence), or whether it definitely cannot play media of that type.

A type that the user agent knows it cannot render is one that describes a resource that the user agent definitely does not support, for example because it doesn't recognize the container type, or it doesn't support the listed codecs.

"application/octet-stream" is special-cased here; if any parameter appears with it, it should be treated just like any other MIME type. This is a deviation from the rule that unknown MIME type parameters should be ignored.

The type attribute of the source element allows the user agent to avoid downloading resources that use formats it cannot render.

4.8.10.4 Network states

4.8.10.5 Loading the media resource

The preload attribute is an enumerated attribute. The following table lists the keywords and states for the attribute â€” the keywords in the left column map to the states in the cell in the second column on the same row as the keyword. The attribute can be changed even once the media resource is being buffered or played; the descriptions in the table below are to be interpreted with that in mind.

Keyword	State	Brief description
`none`	None	Hints to the user agent that either the author does not expect the user to need the media resource, or that the server wants to minimise unnecessary traffic. This state does not provide a hint regarding how aggressively to actually download the media resource if buffering starts anyway (e.g. once the user hits "play").
`metadata`	Metadata	Hints to the user agent that the author does not expect the user to need the media resource, but that fetching the resource metadata (dimensions, first frame, track list, duration, etc) is reasonable. If the user agent precisely fetches no more than the metadata, then the media element will end up with its `readyState` attribute set to `HAVE_METADATA`; typically though, some frames will be obtained as well and it will probably be `HAVE_CURRENT_DATA` or `HAVE_FUTURE_DATA`. When the media resource is playing, hints to the user agent that bandwidth is to be considered scarce, e.g. suggesting throttling the download so that the media data is obtained at the slowest possible rate that still maintains consistent playback.
`auto`	Automatic	Hints to the user agent that the user agent can put the user's needs first without risk to the server, up to and including optimistically downloading the entire resource.

The empty string is also a valid keyword, and maps to the Automatic state. The attribute's missing value default is user-agent defined, though the Metadata state is suggested as a compromise between reducing server load and providing an optimal user experience.

Authors might switch the attribute from "none" or "metadata" to "auto" dynamically once the user begins playback. For example, on a page with many videos this might be used to indicate that the many videos are not to be downloaded unless requested, but that once one is requested it is to be downloaded aggressively.

The autoplay attribute can override the preload attribute (since if the media plays, it naturally has to buffer first, regardless of the hint given by the preload attribute). Including both is not an error, however.

4.8.10.6 Offsets into the media resource

The startOffsetTime attribute must return a new Date object representing the current timeline offset.

4.8.10.7 Ready states

In practice, the difference between HAVE_METADATA and HAVE_CURRENT_DATA is negligible. Really the only time the difference is relevant is when painting a video element onto a canvas, where it distinguishes the case where something will be drawn (HAVE_CURRENT_DATA or greater) from the case where nothing is drawn (HAVE_METADATA or less). Similarly, the difference between HAVE_CURRENT_DATA (only the current frame) and HAVE_FUTURE_DATA (at least this frame and the next) can be negligible (in the extreme, only one frame). The only time that distinction really matters is when a page provides an interface for "frame-by-frame" navigation.

It is possible for the ready state of a media element to jump between these states discontinuously. For example, the state of a media element can jump straight from HAVE_METADATA to HAVE_ENOUGH_DATA without passing through the HAVE_CURRENT_DATA and HAVE_FUTURE_DATA states.

The autoplay attribute is a boolean attribute. When present, the user agent will automatically begin playback of the media resource as soon as it can do so without stopping.

Authors are urged to use the autoplay attribute rather than using script to trigger automatic playback, as this allows the user to override the automatic playback when it is not desired, e.g. when using a screen reader. Authors are also encouraged to consider not using the automatic playback behavior at all, and instead to let the user agent wait for the user to start playback explicitly.

The autoplay IDL attribute must reflect the content attribute of the same name.

4.8.10.8 Playing the media resource

4.8.10.9 Seeking

4.8.10.10 Media resources with multiple media tracks

A media resource can have multiple embedded audio and video tracks. For example, in addition to the primary video and audio tracks, a media resource could have foreign-language dubbed dialogues, director's commentaries, audio descriptions, alternative angles, or sign-language overlays.

4.8.10.10.1 AudioTrackList and VideoTrackList objects

Return values for `AudioTrack.kind()` and `VideoTrack.kind()`
Category	Definition	Applies to...	Examples
"`alternative`"	A possible alternative to the main track, e.g. a different take of a song (audio), or a different angle (video).	Audio and video.	Ogg: "audio/alternate" or "video/alternate".
"`description`"	An audio description of a video track.	Audio only.	Ogg: "audio/audiodesc".
"`main`"	The primary audio or video track.	Audio and video.	Ogg: "audio/main" or "video/main"; WebM: the "FlagDefault" element is set.
"`sign`"	A sign-language interpretation of an audio track.	Video only.	Ogg: "video/sign".
"`translation`"	A translated version of the main track.	Audio only.	Ogg: "audio/dub".
"`commentary`"	Commentary on the primary audio or video track, e.g. a director's commentary.	Audio and video.	No known formats expose this category at this time.
"" (empty string)	No explicit kind, or the kind given by the track's metadata is not recognised by the user agent.	Audio and video.	Any other track type or track role.

4.8.10.10.2 Selecting specific audio and video tracks declaratively

The audioTracks and videoTracks attributes allow scripts to select which track should play, but it is also possible to select specific tracks declaratively, by specifying particular tracks in the fragment identifier of the URL of the media resource. The format of the fragment identifier depends on the MIME type of the media resource. [RFC2046] [RFC3986]

4.8.10.11 Synchronising multiple media elements

4.8.10.11.1 Introduction

Each media element can have a MediaController. A MediaController is an object that coordinates the playback of multiple media elements, for instance so that a sign-language interpreter track can be overlaid on a video track, with the two being kept in sync.

Media elements with a MediaController are said to be slaved to their controller. The MediaController modifies the playback rate and the playback volume of each of the media elements slaved to it, and ensures that when any of its slaved media elements unexpectedly stall, the others are stopped at the same time.

4.8.10.11.2 Media controllers

4.8.10.11.3 Assigning a media controller declaratively

The mediagroup content attribute on media elements can be used to link multiple media elements together by implicitly creating a MediaController. The value is text; media elements with the same value are automatically linked by the user agent.

4.8.10.12 Timed text tracks

4.8.10.12.1 Text track model

A text track cue is the unit of time-sensitive data in a text track, corresponding for instance for subtitles and captions to the text that appears at a particular time and disappears at another time.

The text track cues of a media element's text tracks are ordered relative to each other in the text track cue order, which is determined as follows: first group the cues by their text track, with the groups being sorted in the same order as their text tracks appear in the media element's list of text tracks; then, within each group, cues must be sorted by their start time, earliest first; then, any cues with the same start time must be sorted by their end time, latest first; and finally, any cues with identical end times must be sorted in the order they were created (so e.g. for cues from a WebVTT file, that would be the order in which the cues were listed in the file). [WEBVTT]

4.8.10.12.2 Sourcing in-band text tracks

A media-resource-specific text track is a text track that corresponds to data found in the media resource.

4.8.10.12.3 Text track API

4.8.10.12.4 Text tracks describing chapters

Chapters are segments of a media resource with a given title. Chapters can be nested, in the same way that sections in a document outline can have subsections.

4.8.10.13 User interface

The controls attribute is a boolean attribute. If present, it indicates that the author has not provided a scripted controller and would like the user agent to provide its own set of controls.

The controls IDL attribute must reflect the content attribute of the same name.

This attribute has no dynamic effect (it only controls the default state of the element).

4.8.10.14 Time ranges

Objects implementing the TimeRanges interface represent a list of ranges (periods) of time.

4.8.10.15 Event definitions

4.8.10.16 Event summary

The following events fire on media elements as part of the processing model described above:

Event name	Interface	Fired when...	Preconditions
`loadstart`	`Event`	The user agent begins looking for media data, as part of the resource selection algorithm.	`networkState` equals `NETWORK_LOADING`
`progress`	`Event`	The user agent is fetching media data.	`networkState` equals `NETWORK_LOADING`
`suspend`	`Event`	The user agent is intentionally not currently fetching media data.	`networkState` equals `NETWORK_IDLE`
`abort`	`Event`	The user agent stops fetching the media data before it is completely downloaded, but not due to an error.	`error` is an object with the code `MEDIA_ERR_ABORTED`. `networkState` equals either `NETWORK_EMPTY` or `NETWORK_IDLE`, depending on when the download was aborted.
`error`	`Event`	An error occurs while fetching the media data.	`error` is an object with the code `MEDIA_ERR_NETWORK` or higher. `networkState` equals either `NETWORK_EMPTY` or `NETWORK_IDLE`, depending on when the download was aborted.
`emptied`	`Event`	A media element whose `networkState` was previously not in the `NETWORK_EMPTY` state has just switched to that state (either because of a fatal error during load that's about to be reported, or because the `load()` method was invoked while the resource selection algorithm was already running).	`networkState` is `NETWORK_EMPTY`; all the IDL attributes are in their initial states.
`stalled`	`Event`	The user agent is trying to fetch media data, but data is unexpectedly not forthcoming.	`networkState` is `NETWORK_LOADING`.
`loadedmetadata`	`Event`	The user agent has just determined the duration and dimensions of the media resource and the text tracks are ready.	`readyState` is newly equal to `HAVE_METADATA` or greater for the first time.
`loadeddata`	`Event`	The user agent can render the media data at the current playback position for the first time.	`readyState` newly increased to `HAVE_CURRENT_DATA` or greater for the first time.
`canplay`	`Event`	The user agent can resume playback of the media data, but estimates that if playback were to be started now, the media resource could not be rendered at the current playback rate up to its end without having to stop for further buffering of content.	`readyState` newly increased to `HAVE_FUTURE_DATA` or greater.
`canplaythrough`	`Event`	The user agent estimates that if playback were to be started now, the media resource could be rendered at the current playback rate all the way to its end without having to stop for further buffering.	`readyState` is newly equal to `HAVE_ENOUGH_DATA`.
`playing`	`Event`	Playback is ready to start after having been paused or delayed due to lack of media data.	`readyState` is newly equal to or greater than `HAVE_FUTURE_DATA` and `paused` is false, or `paused` is newly false and `readyState` is equal to or greater than `HAVE_FUTURE_DATA`. Even if this event fires, the element might still not be potentially playing, e.g. if the element is blocked on its media controller (e.g. because the current media controller is paused, or another slaved media element is stalled somehow, or because the media resource has no data corresponding to the media controller position), or the element is paused for user interaction or paused for in-band content.
`waiting`	`Event`	Playback has stopped because the next frame is not available, but the user agent expects that frame to become available in due course.	`readyState` is equal to or less than `HAVE_CURRENT_DATA`, and `paused` is false. Either `seeking` is true, or the current playback position is not contained in any of the ranges in `buffered`. It is possible for playback to stop for other reasons without `paused` being false, but those reasons do not fire this event (and when those situations resolve, a separate `playing` event is not fired either): e.g. the element is newly blocked on its media controller, or playback ended, or playback stopped due to errors, or the element has paused for user interaction or paused for in-band content.
`seeking`	`Event`	The `seeking` IDL attribute changed to true.
`seeked`	`Event`	The `seeking` IDL attribute changed to false.
`ended`	`Event`	Playback has stopped because the end of the media resource was reached.	`currentTime` equals the end of the media resource; `ended` is true.
`durationchange`	`Event`	The `duration` attribute has just been updated.
`timeupdate`	`Event`	The current playback position changed as part of normal playback or in an especially interesting way, for example discontinuously.
`play`	`Event`	The element is no longer paused. Fired after the `play()` method has returned, or when the `autoplay` attribute has caused playback to begin.	`paused` is newly false.
`pause`	`Event`	The element has been paused. Fired after the `pause()` method has returned.	`paused` is newly true.
`ratechange`	`Event`	Either the `defaultPlaybackRate` or the `playbackRate` attribute has just been updated.
`volumechange`	`Event`	Either the `volume` attribute or the `muted` attribute has changed. Fired after the relevant attribute's setter has returned.

Event name	Interface	Fired when...
`emptied`	`Event`	All the slaved media elements newly have `readyState` set to `HAVE_NOTHING` or greater, or there are no longer any slaved media elements.
`loadedmetadata`	`Event`	All the slaved media elements newly have `readyState` set to `HAVE_METADATA` or greater.
`loadeddata`	`Event`	All the slaved media elements newly have `readyState` set to `HAVE_CURRENT_DATA` or greater.
`canplay`	`Event`	All the slaved media elements newly have `readyState` set to `HAVE_FUTURE_DATA` or greater.
`canplaythrough`	`Event`	All the slaved media elements newly have `readyState` set to `HAVE_ENOUGH_DATA` or greater.
`playing`	`Event`	The `MediaController` is no longer a blocked media controller.
`ended`	`Event`	The `MediaController` has reached the end of all the slaved media elements.
`waiting`	`Event`	The `MediaController` is now a blocked media controller.
`ended`	`Event`	All the slaved media elements have newly ended playback.
`durationchange`	`Event`	The `duration` attribute has just been updated.
`timeupdate`	`Event`	The media controller position changed.
`play`	`Event`	The `paused` attribute is newly false.
`pause`	`Event`	The `paused` attribute is newly true.
`ratechange`	`Event`	Either the `defaultPlaybackRate` attribute or the `playbackRate` attribute has just been updated.
`volumechange`	`Event`	Either the `volume` attribute or the `muted` attribute has just been updated.

4.8.10.17 Best practices for authors using media elements

Playing audio and video resources on small devices such as set-top boxes or mobile phones is often constrained by limited hardware resources in the device. For example, a device might only support three simultaneous videos. For this reason, it is a good practice to release resources held by media elements when they are done playing, either by being very careful about removing all references to the element and allowing it to be garbage collected, or, even better, by removing the element's src attribute and any source element descendants, and invoking the element's load() method.

Similarly, when the playback rate is not exactly 1.0, hardware, software, or format limitations can cause video frames to be dropped and audio to be choppy or muted.

4.8.11 The canvas element

The canvas element provides scripts with a resolution-dependent bitmap canvas, which can be used for rendering graphs, game graphics, or other visual images on the fly.

Authors should not use the canvas element in a document when a more suitable element is available. For example, it is inappropriate to use a canvas element to render a page heading: if the desired presentation of the heading is graphically intense, it should be marked up using appropriate elements (typically h1) and then styled using CSS and supporting technologies such as XBL.

When authors use the canvas element, they must also provide content that, when presented to the user, conveys essentially the same function or purpose as the bitmap canvas. This content may be placed as content of the canvas element. The contents of the canvas element, if any, are the element's fallback content.

In non-interactive, static, visual media, if the canvas element has been previously painted on (e.g. if the page was viewed in an interactive visual medium and is now being printed, or if some script that ran during the page layout process painted on the element), then the canvas element represents embedded content with the current image and size. Otherwise, the element represents its fallback content instead.

When a canvas element represents embedded content, the user can still focus descendants of the canvas element (in the fallback content). When an element is focused, it is the target of keyboard interaction events (even though the element itself is not visible). This allows authors to make an interactive canvas keyboard-accessible: authors should have a one-to-one mapping of interactive regions to focusable elements in the fallback content. (Focus has no effect on mouse interaction events.) [DOMEVENTS]

The canvas element has two attributes to control the size of the coordinate space: width and height. These attributes, when specified, must have values that are valid non-negative integers. The width attribute defaults to 300, and the height attribute defaults to 150.

The intrinsic dimensions of the canvas element equal the size of the coordinate space, with the numbers interpreted in CSS pixels. However, the element can be sized arbitrarily by a style sheet. During rendering, the image is scaled to fit this layout size.

The width and height IDL attributes must reflect the respective content attributes of the same name, with the same defaults.

Type	Other arguments	Reference
`image/jpeg`	The second argument is a number in the range 0.0 to 1.0 inclusive treated as the desired quality level.	[JPEG]

4.8.12 The map element

The map element, in conjunction with any area element descendants, defines an image map. The element represents its children.

The name attribute gives the map a name so that it can be referenced. The attribute must be present and must have a non-empty value with no space characters. The value of the name attribute must not be a compatibility-caseless match for the value of the name attribute of another map element in the same document. If the id attribute is also specified, both attributes must have the same value.

4.8.13 The area element

The area element represents either a hyperlink with some text and a corresponding area on an image map, or a dead area on an image map.

If the area element has an href attribute, then the area element represents a hyperlink. In this case, the alt attribute must be present. It specifies the text of the hyperlink. Its value must be text that, when presented with the texts specified for the other hyperlinks of the image map, and with the alternative text of the image, but without the image itself, provides the user with the same kind of choice as the hyperlink would when used without its text but with its shape applied to the image. The alt attribute may be left blank if there is another area element in the same image map that points to the same resource and has a non-blank alt attribute.

If the area element has no href attribute, then the area represented by the element cannot be selected, and the alt attribute must be omitted.

The shape attribute is an enumerated attribute. The following table lists the keywords defined for this attribute. The states given in the first cell of the rows with keywords give the states to which those keywords map.

The attribute may be omitted. The missing value default is the rectangle state.

The coords attribute must, if specified, contain a valid list of integers. This attribute gives the coordinates for the shape described by the shape attribute.

In the circle state, area elements must have a coords attribute present, with three integers, the last of which must be non-negative. The first integer must be the distance in CSS pixels from the left edge of the image to the center of the circle, the second integer must be the distance in CSS pixels from the top edge of the image to the center of the circle, and the third integer must be the radius of the circle, again in CSS pixels.

In the default state state, area elements must not have a coords attribute. (The area is the whole image.)

In the polygon state, area elements must have a coords attribute with at least six integers, and the number of integers must be even. Each pair of integers must represent a coordinate given as the distances from the left and the top of the image in CSS pixels respectively, and all the coordinates together must represent the points of the polygon, in order.

In the rectangle state, area elements must have a coords attribute with exactly four integers, the first of which must be less than the third, and the second of which must be less than the fourth. The four points must represent, respectively, the distance from the left edge of the image to the left side of the rectangle, the distance from the top edge to the top side, the distance from the left edge to the right side, and the distance from the top edge to the bottom side, all in CSS pixels.

The IDL attributes alt, coords, href, target, rel, media, hreflang, and type, each must reflect the respective content attributes of the same name.

The area element also supports the complement of URL decomposition IDL attributes, protocol, host, port, hostname, pathname, search, and hash. These must follow the rules given for URL decomposition IDL attributes, with the input being the result of resolving the element's href attribute relative to the element, if there is such an attribute and resolving it is successful, or the empty string otherwise; and the common setter action being the same as setting the element's href attribute to the new output value.

4.8.14 Image maps

An image map allows geometric areas on an image to be associated with hyperlinks.

An image, in the form of an img element or an object element representing an image, may be associated with an image map (in the form of a map element) by specifying a usemap attribute on the img or object element. The usemap attribute, if specified, must be a valid hash-name reference to a map element.

4.8.15 MathML

4.8.16 SVG

When the SVG foreignObject element contains elements from the HTML namespace, such elements must all be flow content. [SVG]

The content model for title elements in the SVG namespace inside HTML documents is phrasing content. (This further constrains the requirements given in the SVG specification.)

The SVG specification includes requirements regarding the handling of elements in the DOM that are not in the SVG namespace, that are in SVG fragments, and that are not included in a foreignObject element. This specification does not define any processing for elements in SVG fragments that are not in the HTML namespace; they are considered neither conforming nor non-conforming from the perspective of this specification.

4.8.17 Dimension attributes

The width and height attributes on img, iframe, embed, object, video, and, when their type attribute is in the Image Button state, input elements may be specified to give the dimensions of the visual content of the element (the width and height respectively, relative to the nominal direction of the output medium), in CSS pixels. The attributes, if specified, must have values that are valid non-negative integers.

The specified dimensions given may differ from the dimensions specified in the resource itself, since the resource may have a resolution that differs from the CSS pixel resolution. (On screens, CSS pixels have a resolution of 96ppi, but in general the CSS pixel resolution depends on the reading distance.) If both attributes are specified, then one of the following statements must be true:

The target ratio is the ratio of the intrinsic width to the intrinsic height in the resource. The specified width and specified height are the values of the width and height attributes respectively.

The two attributes must be omitted if the resource in question does not have both an intrinsic width and an intrinsic height.

If the two attributes are both zero, it indicates that the element is not intended for the user (e.g. it might be a part of a service to count page views).

The width and height IDL attributes on the iframe, embed, object, and video elements must reflect the respective content attributes of the same name.

4.9 Tabular data

4.9.1 The table element

The table element represents data with more than one dimension, in the form of a table.

Tables have rows, columns, and cells given by their descendants. The rows and columns form a grid; a table's cells must completely cover that grid without overlap.

Authors are encouraged to provide information describing how to interpret complex tables. Guidance on how provide such information is given below.

Tables should not be used as layout aids. Historically, many Web authors have tables in HTML as a way to control their page layout making it difficult to extract tabular data from such documents. In particular, users of accessibility tools, like screen readers, are likely to find it very difficult to navigate pages with tables used for layout. If a table is to be used for layout it must be marked with the attribute role="presentation" for a user agent to properly represent the table to an assistive technology and to properly convey the intent of the author to tools that wish to extract tabular data from the document.

There are a variety of alternatives to using HTML tables for layout, primarily using CSS positioning and the CSS table model.

The border attribute may be specified on a table element to explicitly indicate that the table element is not being used for layout purposes. If specified, the attribute's value must either be the empty string or the value "1". The attribute is used by certain user agents as an indication that borders should be drawn around cells of the table.

Authors are encouraged to consider using some of the table layout techniques described below to make tables easier to navigate for users.

4.9.1.1 Techniques for describing tables

For tables that consist of more than just a grid of cells with headers in the first row and headers in the first column, and for any table in general where the reader might have difficulty understanding the content, authors should include explanatory information introducing the table. This information is useful for all users, but is especially useful for users who cannot see the table, e.g. users of screen readers.

Such explanatory information should introduce the purpose of the table, outline its basic cell structure, highlight any trends or patterns, and generally teach the user how to use the table.

...might benefit from a description explaining the way the table is laid out, something like "Characteristics are given in the second column, with the negative side in the left column and the positive side in the right column".

Authors may also use other techniques, or combinations of the above techniques, as appropriate.

The best option, of course, rather than writing a description explaining the way the table is laid out, is to adjust the table such that no explanation is needed.

Characteristics with positive and negative sides
Negative	Characteristic	Positive
Sad	Mood	Happy
Failing	Grade	Passing

4.9.1.2 Techniques for table layout

In visual media, providing column and row borders and alternating row backgrounds can be very effective to make complicated tables more readable.

For tables with large volumes of numeric content, using monospaced fonts can help users see patterns, especially in situations where a user agent does not render the borders. (Unfortunately, for historical reasons, not rendering borders on tables is a common default.)

In speech media, table cells can be distinguished by reporting the corresponding headers before reading the cell's contents, and by allowing users to navigate the table in a grid fashion, rather than serializing the entire contents of the table in source order.

4.9.2 The caption element

The caption element represents the title of the table that is its parent, if it has a parent and that is a table element.

When a table element is the only content in a figure element other than the figcaption, the caption element should be omitted in favor of the figcaption.

A caption can introduce context for a table, making it significantly easier to understand.

	1	2	3	4	5	6
1	2	3	4	5	6	7
2	3	4	5	6	7	8
3	4	5	6	7	8	9
4	5	6	7	8	9	10
5	6	7	8	9	10	11
6	7	8	9	10	11	12

4.9.3 The colgroup element

If the colgroup element contains no col elements, then the element may have a span content attribute specified, whose value must be a valid non-negative integer greater than zero.

4.9.4 The col element

The element may have a span content attribute specified, whose value must be a valid non-negative integer greater than zero.

4.9.5 The tbody element

The tbody element represents a block of rows that consist of a body of data for the parent table element, if the tbody element has a parent and it is a table.

4.9.6 The thead element

The thead element represents the block of rows that consist of the column labels (headers) for the parent table element, if the thead element has a parent and it is a table.

4.9.7 The tfoot element

The tfoot element represents the block of rows that consist of the column summaries (footers) for the parent table element, if the tfoot element has a parent and it is a table.

4.9.8 The tr element

4.9.9 The td element

4.9.10 The th element

The th element may have a scope content attribute specified. The scope attribute is an enumerated attribute with five states, four of which have explicit keywords:

ID	Measurement	Average	Maximum
	Cats
93	Legs	3.5	4
10	Tails	1	1
	English speakers
32	Legs	2.67	4
35	Tails	0.33	1

4.9.11 Attributes common to td and th elements

The td and th elements may have a colspan content attribute specified, whose value must be a valid non-negative integer greater than zero.

The td and th elements may also have a rowspan content attribute specified, whose value must be a valid non-negative integer.

These attributes give the number of columns and rows respectively that the cell is to span. These attributes must not be used to overlap cells.

The td and th element may have a headers content attribute specified. The headers attribute, if specified, must contain a string consisting of an unordered set of unique space-separated tokens that are case-sensitive, each of which must have the value of an ID of a th element taking part in the same table as the td or th element.

A th element with ID id is said to be directly targeted by all td and th elements in the same table that have headers attributes whose values include as one of their tokens the ID id. A th element A is said to be targeted by a th or td element B if either A is directly targeted by B or if there exists an element C that is itself targeted by the element B and A is directly targeted by C.

The td and th elements implement interfaces that inherit from the HTMLTableCellElement interface:

The headers IDL attribute must reflect the content attribute of the same name.

4.9.12 Examples

The following shows how might one mark up the bottom part of table 45 of the Smithsonian physical tables, Volume 71:

The following shows how one might mark up the gross margin table on page 46 of Apple, Inc's 10-K filing for fiscal year 2008:

The following shows how one might mark up the operating expenses table from lower on the same page of that document:

Specification values: **Steel**, **Castings**, Ann. A.S.T.M. A27-16, Class B;* P max. 0.06; S max. 0.05.
Grade.	Yield Point.	Ultimate tensile strength	Per cent elong. 50.8 mm or 2 in.	Per cent reduct. area.
Hard	0.45 ultimate	56.2	80,000	15	20
Medium	0.45 ultimate	49.2	70,000	18	25
Soft	0.45 ultimate	42.2	60,000	22	30

	2008	2007	2006
Research and development	$ 1,109	$ 782	$ 712
Percentage of net sales	3.4%	3.3%	3.7%
Selling, general, and administrative	$ 3,761	$ 2,963	$ 2,433
Percentage of net sales	11.6%	12.3%	12.6%

4.10 Forms

4.10.1 Introduction

A form is a component of a Web page that has form controls, such as text fields, buttons, checkboxes, range controls, or color pickers. A user can interact with such a form, providing data that can then be sent to the server for further processing (e.g. returning the results of a search or calculation). No client-side scripting is needed in many cases, though an API is available so that scripts can augment the user experience or use forms for purposes other than submitting data to a server.

Writing a form consists of several steps, which can be performed in any order: writing the user interface, implementing the server-side processing, and configuring the user interface to communicate with the server.

4.10.1.1 Writing a form's user interface

For the purposes of this brief introduction, we will create a pizza ordering form.

Any form starts with a form element, inside which are placed the controls. Most controls are represented by the input element, which by default provides a one-line text field. To label a control, the label element is used; the label text and the control itself go inside the label element. Each part of a form is considered a paragraph, and is typically separated from other parts using p elements. Putting this together, here is how one might ask for the customer's name:

To let the user select the size of the pizza, we can use a set of radio buttons. Radio buttons also use the input element, this time with a type attribute with the value radio. To make the radio buttons work as a group, they are given a common name using the name attribute. To group a batch of controls together, such as, in this case, the radio buttons, one can use the fieldset element. The title of such a group of controls is given by the first element in the fieldset, which has to be a legend element.

To pick toppings, we can use checkboxes. These use the input element with a type attribute with the value checkbox:

The pizzeria for which this form is being written is always making mistakes, so it needs a way to contact the customer. For this purpose, we can use form controls specifically for telephone numbers (input elements with their type attribute set to tel) and e-mail addresses (input elements with their type attribute set to email):

We can use an input element with its type attribute set to time to ask for a delivery time. Many of these form controls have attributes to control exactly what values can be specified; in this case, three attributes of particular interest are min, max, and step. These set the minimum time, the maximum time, and the interval between allowed values (in seconds). This pizzeria only delivers between 11am and 9pm, and doesn't promise anything better than 15 minute increments, which we can mark up as follows:

The textarea element can be used to provide a free-form text field. In this instance, we are going to use it to provide a space for the customer to give delivery instructions:

4.10.1.2 Implementing the server-side processing for a form

The exact details for writing a server-side processor are out of scope for this specification. For the purposes of this introduction, we will assume that the script at https://pizza.example.com/order.cgi is configured to accept submissions using the application/x-www-form-urlencoded format, expecting the following parameters sent in an HTTP POST body:

4.10.1.3 Configuring a form to communicate with a server

Form submissions are exposed to servers in a variety of ways, most commonly as HTTP GET or POST requests. To specify the exact method used, the method attribute is specified on the form element. This doesn't specify how the form data is encoded, though; to specify that, you use the enctype attribute. You also have to specify the URL of the service that will handle the submitted data, using the action attribute.

For each form control you want submitted, you then have to give a name that will be used to refer to the data in the submission. We already specified the name for the group of radio buttons; the same attribute (name) also specifies the submission name. Radio buttons can be distinguished from each other in the submission by giving them different values, using the value attribute.

Multiple controls can have the same name; for example, here we give all the checkboxes the same name, and the server distinguishes which checkbox was checked by seeing which values are submitted with that name â€” like the radio buttons, they are also given unique values with the value attribute.

For example, if the customer entered "Denise Lawrence" as their name, "555-321-8642" as their telephone number, did not specify an e-mail address, asked for a medium-sized pizza, selected the Extra Cheese and Mushroom toppings, entered a delivery time of 7pm, and left the delivery instructions text field blank, the user agent would submit the following to the online Web service:

4.10.1.4 Client-side form validation

Forms can be annotated in such a way that the user agent will check the user's input before the form is submitted. The server still has to verify the input is valid (since hostile users can easily bypass the form validation), but it allows the user to avoid the wait incurred by having the server be the sole checker of the user's input.

The simplest annotation is the required attribute, which can be specified on input elements to indicate that the form is not to be submitted until a value is given. By adding this attribute to the customer name and delivery time fields, we allow the user agent to notify the user when the user submits the form without filling in those fields:

It is also possible to limit the length of the input, using the maxlength attribute. By adding this to the textarea element, we can limit users to 1000 characters, preventing them from writing huge essays to the busy delivery drivers instead of staying focused and to the point:

4.10.2 Categories

Mostly for historical reasons, elements in this section fall into several overlapping (but subtly different) categories in addition to the usual ones like flow content, phrasing content, and interactive content.

A number of the elements are form-associated elements, which means they can have a form owner and, to expose this, have a form content attribute with a matching form IDL attribute.

Some elements, not all of them form-associated, are categorized as labelable elements. These are elements that can be associated with a label element.

4.10.3 The form element

The form element represents a collection of form-associated elements, some of which can represent editable values that can be submitted to a server for processing.

The name attribute represents the form's name within the forms collection. The value must not be the empty string, and the value must be unique amongst the form elements in the forms collection that it is in, if any.

The autocomplete attribute is an enumerated attribute. The attribute has two states. The on keyword maps to the on state, and the off keyword maps to the off state. The attribute may also be omitted. The missing value default is the on state. The off state indicates that by default, input elements in the form will have their resulting autocompletion state set to off; the on state indicates that by default, input elements in the form will have their resulting autocompletion state set to on.

The acceptCharset IDL attribute must reflect the accept-charset content attribute.

4.10.4 The fieldset element

The fieldset element represents a set of form controls optionally grouped under a common name.

The name of the group is given by the first legend element that is a child of the fieldset element, if any. The remainder of the descendants form the group.

The disabled attribute, when specified, causes all the form control descendants of the fieldset element, excluding those that are descendants of the fieldset element's first legend element child, if any, to be disabled.

The form attribute is used to explicitly associate the fieldset element with its form owner. The name attribute represents the element's name.

The disabled IDL attribute must reflect the content attribute of the same name.

4.10.5 The legend element

The legend element represents a caption for the rest of the contents of the legend element's parent fieldset element.

4.10.6 The label element

The label represents a caption in a user interface. The caption can be associated with a specific form control, either using for attribute, or by putting the form control inside the label element itself.

The for attribute may be specified to indicate a form control with which the caption is to be associated. If the attribute is specified, the attribute's value must be the ID of a labelable element in the same Document as the label element.

The form attribute is used to explicitly associate the label element with its form owner.

4.10.7 The input element

The input element represents a typed data field, usually with a form control to allow the user to edit the data.

The type attribute controls the data type (and associated control) of the element. It is an enumerated attribute. The following table lists the keywords and states for the attribute â€” the keywords in the left column map to the states in the cell in the second column on the same row as the keyword.

Keyword	State	Data type	Control type
`hidden`	Hidden	An arbitrary string	n/a
`text`	Text	Text with no line breaks	A text field
`search`	Search	Text with no line breaks	Search field
`tel`	Telephone	Text with no line breaks	A text field
`url`	URL	An absolute IRI	A text field
`email`	E-mail	An e-mail address or list of e-mail addresses	A text field
`password`	Password	Text with no line breaks (sensitive information)	A text field that obscures data entry
`datetime`	Date and Time	A date and time (year, month, day, hour, minute, second, fraction of a second) with the time zone set to UTC	A date and time control
`date`	Date	A date (year, month, day) with no time zone	A date control
`month`	Month	A date consisting of a year and a month with no time zone	A month control
`week`	Week	A date consisting of a week-year number and a week number with no time zone	A week control
`time`	Time	A time (hour, minute, seconds, fractional seconds) with no time zone	A time control
`datetime-local`	Local Date and Time	A date and time (year, month, day, hour, minute, second, fraction of a second) with no time zone	A date and time control
`number`	Number	A numerical value	A text field or spinner control
`range`	Range	A numerical value, with the extra semantic that the exact value is not important	A slider control or similar
`color`	Color	An sRGB color with 8-bit red, green, and blue components	A color well
`checkbox`	Checkbox	A set of zero or more values from a predefined list	A checkbox
`radio`	Radio Button	An enumerated value	A radio button
`file`	File Upload	Zero or more files each with a MIME type and optionally a file name	A label and a button
`submit`	Submit Button	An enumerated value, with the extra semantic that it must be the last value selected and initiates form submission	A button
`image`	Image Button	A coordinate, relative to a particular image's size, with the extra semantic that it must be the last value selected and initiates form submission	Either a clickable image, or a button
`reset`	Reset Button	n/a	A button
`button`	Button	n/a	A button

	Hidden	Text, Search	URL, Telephone	E-mail	Password	Date and Time, Date, Month, Week, Time	Local Date and Time	Number	Range	Color	Checkbox, Radio Button	File Upload	Submit Button	Image Button	Reset Button, Button
Content attributes
`accept`	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Yes	Â·	Â·	Â·
`alt`	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Yes	Â·
`autocomplete`	Â·	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Â·	Â·	Â·	Â·	Â·
`checked`	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Yes	Â·	Â·	Â·	Â·
`dirname`	Â·	Yes	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·
`formaction`	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Yes	Yes	Â·
`formenctype`	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Yes	Yes	Â·
`formmethod`	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Yes	Yes	Â·
`formnovalidate`	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Yes	Yes	Â·
`formtarget`	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Yes	Yes	Â·
`height`	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Yes	Â·
`list`	Â·	Yes	Yes	Yes	Â·	Yes	Yes	Yes	Yes	Yes	Â·	Â·	Â·	Â·	Â·
`max`	Â·	Â·	Â·	Â·	Â·	Yes	Yes	Yes	Yes	Â·	Â·	Â·	Â·	Â·	Â·
`maxlength`	Â·	Yes	Yes	Yes	Yes	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·
`min`	Â·	Â·	Â·	Â·	Â·	Yes	Yes	Yes	Yes	Â·	Â·	Â·	Â·	Â·	Â·
`multiple`	Â·	Â·	Â·	Yes	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Yes	Â·	Â·	Â·
`pattern`	Â·	Yes	Yes	Yes	Yes	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·
`placeholder`	Â·	Yes	Yes	Yes	Yes	Â·	Â·	Yes	Â·	Â·	Â·	Â·	Â·	Â·	Â·
`readonly`	Â·	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Â·	Â·	Â·	Â·	Â·	Â·	Â·
`required`	Â·	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Â·	Â·	Yes	Yes	Â·	Â·	Â·
`size`	Â·	Yes	Yes	Yes	Yes	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·
`src`	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Yes	Â·
`step`	Â·	Â·	Â·	Â·	Â·	Yes	Yes	Yes	Yes	Â·	Â·	Â·	Â·	Â·	Â·
`width`	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Yes	Â·
IDL attributes and methods
`checked`	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Yes	Â·	Â·	Â·	Â·
`files`	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Yes	Â·	Â·	Â·
`valueAsDate`	Â·	Â·	Â·	Â·	Â·	Yes	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·
`valueAsNumber`	Â·	Â·	Â·	Â·	Â·	Yes	Yes	Yes	Yes	Â·	Â·	Â·	Â·	Â·	Â·
`list`	Â·	Yes	Yes	Yes	Â·	Yes	Yes	Yes	Yes	Yes	Â·	Â·	Â·	Â·	Â·
`select()`	Â·	Yes	Yes	Â·	Yes	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·
`selectionStart`	Â·	Yes	Yes	Â·	Yes	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·
`selectionEnd`	Â·	Yes	Yes	Â·	Yes	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·
`selectionDirection`	Â·	Yes	Yes	Â·	Yes	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·
`setSelectionRange()`	Â·	Yes	Yes	Â·	Yes	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·	Â·
`stepDown()`	Â·	Â·	Â·	Â·	Â·	Yes	Yes	Yes	Yes	Â·	Â·	Â·	Â·	Â·	Â·
`stepUp()`	Â·	Â·	Â·	Â·	Â·	Yes	Yes	Yes	Yes	Â·	Â·	Â·	Â·	Â·	Â·
Events
`input` event	Â·	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Â·	Â·	Â·	Â·	Â·
`change` event	Â·	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Â·	Â·	Â·

â€ The dagger symbol (â€ ) indicates that the feature only applies when the multiple attribute is not specified.

The form attribute is used to explicitly associate the input element with its form owner. The name attribute represents the element's name. The disabled attribute is used to make the control non-interactive and to prevent its value from being submitted. The autofocus attribute controls focus.

The indeterminate IDL attribute must initially be set to false. On getting, it must return the last value it was set to. On setting, it must be set to the new value. It has no effect except for changing the appearance of checkbox controls.

The accept, alt, max, min, multiple, pattern, placeholder, required, size, src, and step IDL attributes must reflect the respective content attributes of the same name. The dirName IDL attribute must reflect the dirname content attribute. The readOnly IDL attribute must reflect the readonly content attribute. The defaultChecked IDL attribute must reflect the checked content attribute. The defaultValue IDL attribute must reflect the value content attribute.

On setting, they must act as if they reflected the respective content attributes of the same name.

4.10.7.1 States of the type attribute

4.10.7.1.1 Hidden state (type=hidden)

The input element represents a value that is not intended to be examined or manipulated by the user.

If the name attribute is present and has a value that is a case-sensitive match for the string "_charset_", then the element's value attribute must be omitted.

4.10.7.1.2 Text (type=text) state and Search state (type=search)

The input element represents a one line plain text edit control for the element's value.

The difference between the Text state and the Search state is primarily stylistic: on platforms where search fields are distinguished from regular text fields, the Search state might result in an appearance consistent with the platform's search fields rather than appearing like a regular text field.

The value attribute, if specified, must have a value that contains no U+000A LINE FEED (LF) or U+000D CARRIAGE RETURN (CR) characters.

4.10.7.1.3 Telephone state (type=tel)

The input element represents a control for editing a telephone number given in the element's value.

The value attribute, if specified, must have a value that contains no U+000A LINE FEED (LF) or U+000D CARRIAGE RETURN (CR) characters.

Unlike the URL and E-mail types, the Telephone type does not enforce a particular syntax. This is intentional; in practice, telephone number fields tend to be free-form fields, because there are a wide variety of valid phone numbers. Systems that need to enforce a particular format are encouraged to use the pattern attribute or the setCustomValidity() method to hook into the client-side validation mechanism.

4.10.7.1.4 URL state (type=url)

4.10.7.1.5 E-mail state (type=email)

How the E-mail state operates depends on whether the multiple attribute is specified or not.

This requirement is a willful violation of RFC 5322, which defines a syntax for e-mail addresses that is simultaneously too strict (before the "@" character), too vague (after the "@" character), and too lax (allowing comments, whitespace characters, and quoted strings in manners unfamiliar to most users) to be of practical use here.

4.10.7.1.6 Password state (type=password)

The input element represents a one line plain text edit control for the element's value. The user agent should obscure the value so that people other than the user cannot see it.

The value attribute, if specified, must have a value that contains no U+000A LINE FEED (LF) or U+000D CARRIAGE RETURN (CR) characters.

4.10.7.1.7 Date and Time state (type=datetime)

The format shown to the user is independent of the format used for form submission. Browsers are encouraged to use user interfaces that present dates and times according to the conventions of the user's preferred locale.

4.10.7.1.8 Date state (type=date)

The input element represents a control for setting the element's value to a string representing a specific date.

The format shown to the user is independent of the format used for form submission. Browsers are encouraged to use user interfaces that present dates according to the conventions of the user's preferred locale.

The value attribute, if specified and not empty, must have a value that is a valid date string.

The min attribute, if specified, must have a value that is a valid date string. The max attribute, if specified, must have a value that is a valid date string.

4.10.7.1.9 Month state (type=month)

The input element represents a control for setting the element's value to a string representing a specific month.

The format shown to the user is independent of the format used for form submission. Browsers are encouraged to use user interfaces that present months according to the conventions of the user's preferred locale.

The value attribute, if specified and not empty, must have a value that is a valid month string.

4.10.7.1.10 Week state (type=week)

The input element represents a control for setting the element's value to a string representing a specific week.

The format shown to the user is independent of the format used for form submission. Browsers are encouraged to use user interfaces that present weeks according to the conventions of the user's preferred locale.

The value attribute, if specified and not empty, must have a value that is a valid week string.

The min attribute, if specified, must have a value that is a valid week string. The max attribute, if specified, must have a value that is a valid week string.

4.10.7.1.11 Time state (type=time)

The input element represents a control for setting the element's value to a string representing a specific time.

The format shown to the user is independent of the format used for form submission. Browsers are encouraged to use user interfaces that present times according to the conventions of the user's preferred locale.

The value attribute, if specified and not empty, must have a value that is a valid time string.

The min attribute, if specified, must have a value that is a valid time string. The max attribute, if specified, must have a value that is a valid time string.

4.10.7.1.12 Local Date and Time state (type=datetime-local)

The input element represents a control for setting the element's value to a string representing a local date and time, with no time-zone offset information.

4.10.7.1.13 Number state (type=number)

The input element represents a control for setting the element's value to a string representing a number.

This specification does not define what user interface user agents are to use; user agent vendors are encouraged to consider what would best serve their users' needs. For example, a user agent in Persian or Arabic markets might support Persian and Arabic numeric input (converting it to the format required for submission as described above).

The default step is 1 (allowing only integers, unless the min attribute has a non-integer value).

4.10.7.1.14 Range state (type=range)

The input element represents a control for setting the element's value to a string representing a number, but with the caveat that the exact value is not important, letting UAs provide a simpler interface than they do for the Number state.

The default step is 1 (allowing only integers, unless the min attribute has a non-integer value).

4.10.7.1.15 Color state (type=color)

The value attribute, if specified and not empty, must have a value that is a valid simple color.

4.10.7.1.16 Checkbox state (type=checkbox)

The input element represents a two-state control that represents the element's checkedness state. If the element's checkedness state is true, the control represents a positive selection, and if it is false, a negative selection. If the element's indeterminate IDL attribute is set to true, then the control's selection should be obscured as if the control was in a third, indeterminate, state.

The control is never a true tri-state control, even if the element's indeterminate IDL attribute is set to true. The indeterminate IDL attribute only gives the appearance of a third state.

4.10.7.1.17 Radio Button state (type=radio)

The input element represents a control that, when used in conjunction with other input elements, forms a radio button group in which only one control can have its checkedness state set to true. If the element's checkedness state is true, the control represents the selected control in the group, and if it is false, it indicates a control in the group that is not selected.

The radio button group that contains an input element a also contains all the other input elements b that fulfill all of the following conditions:

A document must not contain an input element whose radio button group contains only that element.

If none of the radio buttons in a radio button group are checked when they are inserted into the document, then they will all be initially unchecked in the interface, until such time as one of them is checked (either by the user or by script).

4.10.7.1.18 File Upload state (type=file)

The input element represents a list of selected files, each file consisting of a file name, a file type, and a file body (the contents of the file).

The accept attribute may be specified to provide user agents with a hint of what file types will be accepted.

The tokens must not be ASCII case-insensitive matches for any of the other tokens (i.e. duplicates are not allowed).

User agents may use the value of this attribute to display a more appropriate user interface than a generic file picker. For instance, given the value image/*, a user agent could offer the user the option of using a local camera or selecting a photograph from their photo collection; given the value audio/*, a user agent could offer the user the option of recording a clip using a headset microphone.

4.10.7.1.19 Submit Button state (type=submit)

The formnovalidate attribute can be used to make submit buttons that do not trigger the constraint validation.

4.10.7.1.20 Image Button state (type=image)

The input element represents either an image from which a user can select a coordinate and submit the form, or alternatively a button from which the user can submit the form. The element is a button, specifically a submit button.

The coordinate is sent to the server during form submission by sending two entries for the element, derived from the name of the control but with ".x" and ".y" appended to the name with the x and y components of the coordinate respectively.

The image is given by the src attribute. The src attribute must be present, and must contain a valid non-empty URL potentially surrounded by spaces referencing a non-interactive, optionally animated, image resource that is neither paged nor scripted.

The alt attribute provides the textual label for the alternative button for users and user agents who cannot use the image. The alt attribute must also be present, and must contain a non-empty string.

Many aspects of this state's behavior are similar to the behavior of the img element. Readers are encouraged to read that section, where many of the same requirements are described in more detail.

4.10.7.1.21 Reset Button state (type=reset)

The input element represents a button that, when activated, resets the form. The element is a button.

4.10.7.1.22 Button state (type=button)

The input element represents a button with no default behavior. A label for the button must be provided in the value attribute, though it may be the empty string. The element is a button.

4.10.7.2 Common input element attributes

4.10.7.2.1 The autocomplete attribute

User agents sometimes have features for helping users fill forms in, for example prefilling the user's address based on earlier user input.

The autocomplete attribute is an enumerated attribute. The attribute has three states. The on keyword maps to the on state, and the off keyword maps to the off state. The attribute may also be omitted. The missing value default is the default state.

The off state indicates either that the control's input data is particularly sensitive (for example the activation code for a nuclear weapon); or that it is a value that will never be reused (for example a one-time-key for a bank login) and the user will therefore have to explicitly enter the data each time, instead of being able to rely on the UA to prefill the value for him; or that the document provides its own autocomplete mechanism and does not want the user agent to provide autocompletion values.

Conversely, the on state indicates that the value is not particularly sensitive and the user can expect to be able to rely on his user agent to remember values he has entered for that control.

The default state indicates that the user agent is to use the autocomplete attribute on the element's form owner instead. (By default, the autocomplete attribute of form elements is in the on state.)

4.10.7.2.2 The dirname attribute

4.10.7.2.3 The list attribute

The list attribute is used to identify an element that lists predefined options suggested to the user.

If present, its value must be the ID of a datalist element in the same document.

4.10.7.2.4 The readonly attribute

The readonly attribute is a boolean attribute that controls whether or not the user can edit the form control.

4.10.7.2.5 The size attribute

The size attribute gives the number of characters that, in a visual rendering, the user agent is to allow the user to see while editing the element's value.

4.10.7.2.6 The required attribute

The required attribute is a boolean attribute. When specified, the element is required.

4.10.7.2.7 The multiple attribute

The multiple attribute is a boolean attribute that indicates whether the user is to be allowed to specify more than one value.

4.10.7.2.8 The maxlength attribute

4.10.7.2.9 The pattern attribute

The pattern attribute specifies a regular expression against which the control's value, or, when the multiple attribute applies and is set, the control's values, are to be checked.

If specified, the attribute's value must match the JavaScript Pattern production. [ECMA262]

When an input element has a pattern attribute specified, authors should include a title attribute to give a description of the pattern. User agents may use the contents of this attribute, if it is present, when informing the user that the pattern is not matched, or at any other suitable time, such as in a tooltip or read out by assistive technology when the control gains focus.

When a control has a pattern attribute, the title attribute, if used, must describe the pattern. Additional information could also be included, so long as it assists the user in filling in the control. Otherwise, assistive technology would be impaired.

For instance, if the title attribute contained the caption of the control, assistive technology could end up saying something like The text you have entered does not match the required pattern. Birthday, which is not useful.

UAs may still show the title in non-error situations (for example, as a tooltip when hovering over the control), so authors should be careful not to word titles as if an error has necessarily occurred.

4.10.7.2.10 The min and max attributes

The min and max attributes indicate the allowed range of values for the element.

The max attribute's value (the maximum) must not be less than the min attribute's value (its minimum).

An element has range limitations if it has a defined minimum or a defined maximum.

4.10.7.2.11 The step attribute

The step attribute indicates the granularity that is expected (and required) of the value, by limiting the allowed values.

4.10.7.2.12 The placeholder attribute

The placeholder attribute represents a short hint (a word or short phrase) intended to aid the user with data entry. A hint could be a sample value or a brief description of the expected format. The attribute, if specified, must have a value that contains no U+000A LINE FEED (LF) or U+000D CARRIAGE RETURN (CR) characters.

For a longer hint or other advisory text, the title attribute is more appropriate.

4.10.7.3 Common input element APIs

4.10.8 The button element

The type attribute controls the behavior of the button when it is activated. It is an enumerated attribute. The following table lists the keywords and states for the attribute â€” the keywords in the left column map to the states in the cell in the second column on the same row as the keyword.

Keyword	State	Brief description
`submit`	Submit Button	Submits the form.
`reset`	Reset Button	Resets the form.
`button`	Button	Does nothing.

The formnovalidate attribute can be used to make submit buttons that do not trigger the constraint validation.

The value attribute gives the element's value for the purposes of form submission. The element's value is the value of the element's value attribute, if there is one, or the empty string otherwise.

A button (and its value) is only included in the form submission if the button itself was used to initiate the form submission.

4.10.9 The select element

The select element represents a control for selecting amongst a set of options.

The size attribute gives the number of options to show to the user. The size attribute, if specified, must have a value that is a valid non-negative integer greater than zero.

The list of options for a select element consists of all the option element children of the select element, and all the option element children of all the optgroup element children of the select element, in tree order.

The required attribute is a boolean attribute. When specified, the user will be required to select a value before submitting the form.

If a select element has a required attribute specified, does not have a multiple attribute specified, and has a display size of 1; and if the value of the first option element in the select element's list of options (if any) is the empty string, and that option element's parent node is the select element (and not an optgroup element), then that option is the select element's placeholder label option.

The form attribute is used to explicitly associate the select element with its form owner. The name attribute represents the element's name. The disabled attribute is used to make the control non-interactive and to prevent its value from being submitted. The autofocus attribute controls focus.

The multiple, required, and size IDL attributes must reflect the respective content attributes of the same name. The size IDL attribute has a default value of zero.

4.10.10 The datalist element

The datalist element represents a set of option elements that represent predefined options for other controls. The contents of the element represents fallback content for legacy user agents, intermixed with option elements that represent the predefined options. In the rendering, the datalist element represents nothing.

The datalist element is hooked up to an input element using the list attribute on the input element.

Each option element that is a descendant of the datalist element, that is not disabled, and whose value is a string that isn't the empty string, represents a suggestion. Each suggestion has a value and a label.

4.10.11 The optgroup element

The element's group of option elements consists of the option elements that are children of the optgroup element.

The label attribute must be specified. Its value gives the name of the group, for the purposes of the user interface.

The disabled and label attributes must reflect the respective content attributes of the same name.

4.10.12 The option element

The option element represents an option in a select element or as part of a list of suggestions in a datalist element.

The disabled attribute is a boolean attribute. An option element is disabled if its disabled attribute is present or if it is a child of an optgroup element whose disabled attribute is present.

The label attribute provides a label for element. The label of an option element is the value of the label content attribute, if there is one, or, if there is not, the value of the element's text IDL attribute.

The value attribute provides a value for element. The value of an option element is the value of the value content attribute, if there is one, or, if there is not, the value of the element's text IDL attribute.

A select element whose multiple attribute is not specified must not have more than one descendant option element with its selected attribute set.

The disabled IDL attribute must reflect the content attribute of the same name. The defaultSelected IDL attribute must reflect the selected content attribute.

4.10.13 The textarea element

The textarea element represents a multiline plain text edit control. The contents of the control represent the control's default value.

The readonly attribute is a boolean attribute used to control whether the text can be edited by the user or not.

The cols attribute specifies the expected maximum number of characters per line. If the cols attribute is specified, its value must be a valid non-negative integer greater than zero.

The rows attribute specifies the number of lines to show. If the rows attribute is specified, its value must be a valid non-negative integer greater than zero.

The wrap attribute is an enumerated attribute with two keywords and states: the soft keyword which maps to the Soft state, and the hard keyword which maps to the Hard state. The missing value default is the Soft state.

The Soft state indicates that the text in the textarea is not to be wrapped when it is submitted (though it can still be wrapped in the rendering).

The Hard state indicates that the text in the textarea is to have newlines added by the user agent so that the text is wrapped when it is submitted.

If the element's wrap attribute is in the Hard state, the cols attribute must be specified.

The required attribute is a boolean attribute. When specified, the user will be required to enter a value before submitting the form.

The placeholder attribute represents a hint (a word or short phrase) intended to aid the user with data entry. A hint could be a sample value or a brief description of the expected format. The attribute, if specified, must have a value that contains no U+000A LINE FEED (LF) or U+000D CARRIAGE RETURN (CR) characters.

For a longer hint or other advisory text, the title attribute is more appropriate.

The form attribute is used to explicitly associate the textarea element with its form owner. The name attribute represents the element's name. The disabled attribute is used to make the control non-interactive and to prevent its value from being submitted. The autofocus attribute controls focus.

4.10.14 The keygen element

The keygen element represents a key pair generator control. When the control's form is submitted, the private key is stored in the local keystore, and the public key is packaged and sent to the server.

The challenge attribute may be specified. Its value will be packaged with the submitted key.

The keytype attribute is an enumerated attribute. The following table lists the keywords and states for the attribute â€” the keywords in the left column map to the states listed in the cell in the second column on the same row as the keyword. User agents are not required to support these values, and must only recognize values whose corresponding algorithms they support.

Keyword	State
`rsa`	RSA

The invalid value default state is the unknown state. The missing value default state is the RSA state, if it is supported, or the unknown state otherwise.

This specification does not specify what key types user agents are to support â€” it is possible for a user agent to not support any key types at all.

The form attribute is used to explicitly associate the keygen element with its form owner. The name attribute represents the element's name. The disabled attribute is used to make the control non-interactive and to prevent its value from being submitted. The autofocus attribute controls focus.

The challenge IDL attribute must reflect the content attribute of the same name.

This specification does not specify how the private key generated is to be used. It is expected that after receiving the


SignedPublicKeyAndChallenge

(SPKAC) structure, the server will generate a client certificate and offer it back to the user for download; this certificate, once downloaded and stored in the key store along with the private key, can then be used to authenticate to services that use TLS and certificate authentication.

4.10.15 The output element

The for content attribute allows an explicit relationship to be made between the result of a calculation and the elements that represent the values that went into the calculation or that otherwise influenced the calculation. The for attribute, if specified, must contain a string consisting of an unordered set of unique space-separated tokens that are case-sensitive, each of which must have the value of an ID of an element in the same Document.

The form attribute is used to explicitly associate the output element with its form owner. The name attribute represents the element's name.

4.10.16 The progress element

The progress element represents the completion progress of a task. The progress is either indeterminate, indicating that progress is being made but that it is not clear how much more work remains to be done before the task is complete (e.g. because the task is waiting for a remote host to respond), or the progress is a number in the range zero to a maximum, giving the fraction of work that has so far been completed.

There are two attributes that determine the current task completion represented by the element. The value attribute specifies how much of the task has been completed, and the max attribute specifies how much work the task requires in total. The units are arbitrary and not specified.

To make a determinate progress bar, add a value attribute with the current progress (either a number from 0.0 to 1.0, or, if the max attribute is specified, a number from 0 to the value of the max attribute). To make an indeterminate progress bar, remove the value attribute.

Authors are encouraged to also include the current value and the maximum value inline as text inside the element, so that the progress is made available to users of legacy user agents.

The value and max attributes, when present, must have values that are valid floating point numbers. The value attribute, if present, must have a value equal to or greater than zero, and less than or equal to the value of the max attribute, if present, or 1.0, otherwise. The max attribute, if present, must have a value greater than zero.

The progress element is the wrong element to use for something that is just a gauge, as opposed to task progress. For instance, indicating disk space usage using progress would be inappropriate. Instead, the meter element is available for such use cases.

If the progress bar is an indeterminate progress bar, then the value IDL attribute, on getting, must return 0. Otherwise, it must return the current value. On setting, the given value must be converted to the best representation of the number as a floating point number and then the value content attribute must be set to that string.

4.10.17 The meter element

The meter element represents a scalar measurement within a known range, or a fractional value; for example disk usage, the relevance of a query result, or the fraction of a voting population to have selected a particular candidate.

The meter element should not be used to indicate progress (as in a progress bar). For that role, HTML provides a separate progress element.

The meter element also does not represent a scalar value of arbitrary range â€” for example, it would be wrong to use this to report a weight, or height, unless there is a known maximum value.

There are six attributes that determine the semantics of the gauge represented by the element.

The min attribute specifies the lower bound of the range, and the max attribute specifies the upper bound. The value attribute specifies the value to have the gauge indicate as the "measured" value.

The other three attributes can be used to segment the gauge's range into "low", "medium", and "high" parts, and to indicate which part of the gauge is the "optimum" part. The low attribute specifies the range that is considered to be the "low" part, and the high attribute specifies the range that is considered to be the "high" part. The optimum attribute gives the position that is "optimum"; if that is higher than the "high" value then this indicates that the higher the value, the better; if it's lower than the "low" mark then it indicates that lower values are better, and naturally if it is in between then it indicates that neither high nor low values are good.

If the min attribute attribute is specified, then let minimum be that attribute's value; otherwise, let it be zero.

If the max attribute attribute is specified, then let maximum be that attribute's value; otherwise, let it be 1.0.

If no minimum or maximum is specified, then the range is assumed to be 0..1, and the value thus has to be within that range.

Authors are encouraged to include a textual representation of the gauge's state in the element's contents, for users of user agents that do not support the meter element.

There is no explicit way to specify units in the meter element, but the units may be specified in the title attribute in free-form text.

User agents combine the value of the title attribute and the other attributes to provide context-sensitive help or inline text detailing the actual values.

4.10.18 Association of controls and forms

A form-associated element is, by default, associated with its ancestor form element, but may have a form attribute specified to override this.

This feature allows authors to work around the lack of support for nested form elements.

4.10.19 Attributes common to form controls

4.10.19.1 Naming form controls

The name content attribute gives the name of the form control, as used in form submission and in the form element's elements object. If the attribute is specified, its value must not be the empty string.

Any non-empty value for name is allowed, but the names "_charset_" and "isindex" are special:

4.10.19.2 Enabling and disabling form controls

A form control is disabled if its disabled attribute is set, or if it is a descendant of a fieldset element whose disabled attribute is set and is not a descendant of that fieldset element's first legend element child, if any.

4.10.19.3 Autofocusing a form control

The autofocus content attribute allows the author to indicate that a control is to be focused as soon as the page is loaded, allowing the user to just start typing without having to manually focus the main control.

There must not be more than one element in the document with the autofocus attribute specified.

The autofocus IDL attribute must reflect the content attribute of the same name.

4.10.19.4 Limiting user input length

A form control maxlength attribute, controlled by a dirty value flag, declares a limit on the number of characters a user can input.

4.10.19.5 Form submission

Attributes for form submission can be specified both on form elements and on submit buttons (elements that represent buttons that submit forms, e.g. an input element whose type attribute is in the Submit Button state).

The action of an element is the value of the element's formaction attribute, if the element is a submit button and has such an attribute, or the value of its form owner's action attribute, if it has one, or else the empty string.

The method and formmethod content attributes are enumerated attributes with the following keywords and states:

The method of an element is one of those states. If the element is a submit button and has a formmethod attribute, then the element's method is that attribute's state; otherwise, it is the form owner's method attribute's state.

The enctype and formenctype content attributes are enumerated attributes with the following keywords and states:

The enctype of an element is one of those three states. If the element is a submit button and has a formenctype attribute, then the element's enctype is that attribute's state; otherwise, it is the form owner's enctype attribute's state.

The target of an element is the value of the element's formtarget attribute, if the element is a submit button and has such an attribute; or the value of its form owner's target attribute, if it has such an attribute; or, if the Document contains a base element with a target attribute, then the value of the target attribute of the first such base element; or, if there is no such element, the empty string.

The novalidate and formnovalidate content attributes are boolean attributes. If present, they indicate that the form is not to be validated during submission.

The no-validate state of an element is true if the element is a submit button and the element's formnovalidate attribute is present, or if the element's form owner's novalidate attribute is present, and false otherwise.

The action IDL attribute must reflect the content attribute of the same name, except that on getting, when the content attribute is missing or its value is the empty string, the document's address must be returned instead. The target IDL attribute must reflect the content attribute of the same name. The method and enctype IDL attributes must reflect the respective content attributes of the same name, limited to only known values. The encoding IDL attribute must reflect the enctype content attribute, limited to only known values. The noValidate IDL attribute must reflect the novalidate content attribute. The formAction IDL attribute must reflect the formaction content attribute, except that on getting, when the content attribute is missing or its value is the empty string, the document's address must be returned instead. The formEnctype IDL attribute must reflect the formenctype content attribute, limited to only known values. The formMethod IDL attribute must reflect the formmethod content attribute, limited to only known values. The formNoValidate IDL attribute must reflect the formnovalidate content attribute. The formTarget IDL attribute must reflect the formtarget content attribute.

4.10.19.6 Submitting element directionality

A form control dirname attribute on a form control element enables the submission of the directionality of the element, and gives the name of the field that contains this value during form submission. If such an attribute is specified, its value must not be the empty string.

4.10.20 APIs for the text field selections

The input and textarea elements define the following members in their DOM interfaces for handling their selection:

These methods and attributes expose and control the selection of input and textarea text fields.

Characters with no visible rendering, such as U+200D ZERO WIDTH JOINER, still count as characters. Thus, for instance, the selection can include just an invisible character, and the text insertion cursor can be placed to one side or another of such a character.

4.10.21 Constraints

4.10.21.1 Definitions

4.10.21.2 The constraint validation API

The validity attribute must return a


ValidityState

object that represents the validity states of the element. This object is live, and the same object must be returned each time the element's validity attribute is retrieved.

4.10.21.3 Security

Servers should not rely on client-side validation. Client-side validation can be intentionally bypassed by hostile users, and unintentionally bypassed by users of older user agents or automated tools that do not implement these features. The constraint validation features are only intended to improve the user experience, not to provide any kind of security mechanism.

4.10.22 Form submission

When a form is submitted, the data in the form is converted into the structure specified by the enctype, and then sent to the destination specified by the action using the given method.

If the user types in "cats" in the first field and "fur" in the second, and then hits the submit button, then the user agent will load /find.cgi?t=cats&q=fur.

Given the same user input, the result on submission is quite different: the user agent instead does an HTTP POST to the given URL, with as the entity body something like the following text:

4.10.22.1 URL-encoded form data

This form data set encoding is in many ways an aberrant monstrosity, the result of many years of implementation accidents and compromises leading to a set of requirements necessary for interoperability, but in no way representing good design practices. In particular, readers are cautioned to pay close attention to the twisted details involving repeated (and in some cases nested) conversions between character encodings and byte sequences.

To decode application/x-www-form-urlencoded payloads, the following algorithm should be used. This algorithm uses as inputs the payload itself, payload, consisting of a Unicode string using only characters in the range U+0000 to U+007F; a default character encoding encoding; and optionally an isindex flag indicating that the payload is to be processed as if it had been generated for a form containing an isindex control. The output of this algorithm is a sorted list of name-value pairs. If the isindex flag is set and the first control really was an isindex control, then the first name-value pair will have as its name the empty string.

Parameters on the application/x-www-form-urlencoded MIME type are ignored. In particular, this MIME type does not support the charset parameter.

4.10.22.2 Plain text form data

Payloads using the text/plain format are intended to be human readable. They are not reliably interpretable by computer, as the format is ambiguous (for example, there is no way to distinguish a literal newline in a value from the newline at the end of the value).

4.11 Interactive elements

4.11.1 The details element

The details element represents a disclosure widget from which the user can obtain additional information or controls.

The details element is not appropriate for footnotes. Please see the section on footnotes for details on how to mark up footnotes.

The summary element child of the element, if any, represents the summary or legend of the details.

The rest of the element's contents represents the additional information or controls.

The open content attribute is a boolean attribute. If present, it indicates that both the summary and the additional information is to be shown to the user. If the attribute is absent, only the summary is to be shown.

4.11.2 The summary element

The summary element represents a summary, caption, or legend for the rest of the contents of the summary element's parent details element.

4.11.3 The command element

A command can be part of a context menu or toolbar, using the menu element, or can be put anywhere else in the page, to define a keyboard shortcut.

The type attribute indicates the kind of command: either a normal command with an associated action, or a state or option that can be toggled, or a selection of one item from a list of items.

The attribute is an enumerated attribute with three keywords and states. The "command" keyword maps to the Command state, the "checkbox" keyword maps to the Checkbox state, and the "radio" keyword maps to the Radio state. The missing value default is the Command state.

The label attribute gives the name of the command, as shown to the user. The label attribute must be specified and must have a value that is not the empty string.

The title attribute gives a hint describing the command, which might be shown to the user to help him.

The disabled attribute is a boolean attribute that, if present, indicates that the command is not available in the current state.

The distinction between disabled and hidden is subtle. A command would be disabled if, in the same context, it could be enabled if only certain aspects of the situation were changed. A command would be marked as hidden if, in that situation, the command will never be enabled. For example, in the context menu for a water faucet, the command "open" might be disabled if the faucet is already open, but the command "eat" would be marked hidden since the faucet could never be eaten.

The checked attribute is a boolean attribute that, if present, indicates that the command is selected. The attribute must be omitted unless the type attribute is in either the Checkbox state or the Radio state.

The radiogroup attribute gives the name of the group of commands that will be toggled when the command itself is toggled, for commands whose type attribute has the value "radio". The scope of the name is the child list of the parent element. The attribute must be omitted unless the type attribute is in the Radio state.

The label, icon, disabled, checked, and radiogroup IDL attributes must reflect the respective content attributes of the same name.

4.11.4 The menu element

The type attribute is an enumerated attribute indicating the kind of menu being declared. The attribute has three states. The context keyword maps to the state, in which the element is declaring a context menu. The toolbar keyword maps to the state, in which the element is declaring a toolbar. The attribute may also be omitted. The missing value default is the list state, which indicates that the element is merely a list of commands that is neither declaring a context menu nor defining a toolbar.

If a menu element's type attribute is in the state, then the element represents the commands of a context menu, and the user can only interact with the commands if that context menu is activated.

If a menu element's type attribute is in the state, then the element represents a list of active commands that the user can immediately interact with.

If a menu element's type attribute is in the list state, then the element either represents an unordered list of items (each represented by an li element), each of which represents a command that the user can perform or activate, or, if the element has no li element children, flow content describing available commands.

The label attribute gives the label of the menu. It is used by user agents to display nested menus in the UI. For example, a context menu containing another menu would use the nested menu's label attribute for the submenu's menu label.

The type and label IDL attributes must reflect the respective content attributes of the same name.

4.11.4.1 Introduction

For example, the following represents a toolbar with three menu buttons on it, each of which has a dropdown menu with a series of options:

In a legacy user agent, the above would look like a bulleted list with three items, the first of which has four buttons, the second of which has three, and the third of which has two nested bullet points with two items consisting of links.

The following implements a similar toolbar, with a single button whose values, when selected, redirect the user to Web sites.

The behavior in supporting user agents is similar to the example above, but here the legacy behavior consists of a single select element with a submit button. The submit button doesn't appear in the toolbar, because it is not a child of the menu element or of its li children.

4.11.4.2 Context menus

The contextmenu attribute gives the element's context menu. The value must be the ID of a menu element in the DOM.

The contextMenu IDL attribute must reflect the contextmenu content attribute.

4.11.5 Commands

User agents may expose the commands whose facet is false (visible) and whose elements are in a Document. For example, such commands could be listed in the user agent's menu bar. User agents are encouraged to do this especially for commands that have , as a way to advertise those keys to the user.

4.12 Links

4.12.1 Introduction

Links are a conceptual construct, created by a, area, and link elements, that represent a connection between two resources, one of which is the current Document. There are two kinds of links in HTML:

For link elements with an href attribute and a rel attribute, links must be created for the keywords of the rel attribute, as defined for those keywords in the link types section.

Similarly, for a and area elements with an href attribute and a rel attribute, links must be created for the keywords of the rel attribute as defined for those keywords in the link types section. Unlike link elements, however, a and area element with an href attribute that either do not have a rel attribute, or whose rel attribute has no keywords that are defined as specifying hyperlinks, must also create a hyperlink. This implied hyperlink has no special meaning (it has no link type) beyond linking the element's document to the resource given by the element's href attribute.

A hyperlink can have one or more hyperlink annotations that modify the processing semantics of that hyperlink.

4.12.2 Links created by a and area elements

The href attribute on a and area elements is not required; when those elements do not have href attributes they do not create hyperlinks.

The rel attribute has no default value. If the attribute is omitted or if none of the values in the attribute are recognized by the user agent, then the document has no particular relationship with the destination resource other than there being a hyperlink between the two.

The media attribute describes for which media the target document was designed. It is purely advisory. The value must be a valid media query. The default, if the media attribute is omitted, is "all".

The hreflang attribute on a and area elements that create hyperlinks, if present, gives the language of the linked resource. It is purely advisory. The value must be a valid BCP 47 language tag. [BCP47]

The type attribute, if present, gives the MIME type of the linked resource. It is purely advisory. The value must be a valid MIME type.

4.12.3 Link types

The following table summarizes the link types that are defined by this specification. This table is non-normative; the actual definitions for the link types are given in the next few sections.

In this section, the term referenced document refers to the resource identified by the element representing the link, and the term current document refers to the resource within which the element representing the link finds itself.

Except where otherwise specified, a keyword must not be specified more than once per rel attribute.

Link type	Effect on...	Brief description
`alternate`	Hyperlink	Hyperlink	Gives alternate representations of the current document.
`author`	Hyperlink	Hyperlink	Gives a link to the current document's author.
`bookmark`	not allowed	Hyperlink	Gives the permalink for the nearest ancestor section.
`help`	Hyperlink	Hyperlink	Provides a link to context-sensitive help.
`icon`	External Resource	not allowed	Imports an icon to represent the current document.
`license`	Hyperlink	Hyperlink	Indicates that the main content of the current document is covered by the copyright license described by the referenced document.
`next`	Hyperlink	Hyperlink	Indicates that the current document is a part of a series, and that the next document in the series is the referenced document.
`nofollow`	not allowed	Annotation	Indicates that the current document's original author or publisher does not endorse the referenced document.
`noreferrer`	not allowed	Annotation	Requires that the user agent not send an HTTP `Referer` (sic) header if the user follows the hyperlink.
`prefetch`	External Resource	External Resource	Specifies that the target resource should be preemptively cached.
`prev`	Hyperlink	Hyperlink	Indicates that the current document is a part of a series, and that the previous document in the series is the referenced document.
`search`	Hyperlink	Hyperlink	Gives a link to a resource that can be used to search through the current document and its related pages.
`stylesheet`	External Resource	not allowed	Imports a stylesheet.
`tag`	not allowed	Hyperlink	Gives a tag (identified by the given address) that applies to the current document.

4.12.3.1 Link type "alternate"

4.12.3.2 Link type "author"

The author keyword may be used with link, a, and area elements. This keyword creates a hyperlink.

For a and area elements, the author keyword indicates that the referenced document provides further information about the author of the nearest article element ancestor of the element defining the hyperlink, if there is one, or of the page as a whole, otherwise.

For link elements, the author keyword indicates that the referenced document provides further information about the author for the page as a whole.

The "referenced document" can be, and often is, a mailto: URL giving the e-mail address of the author. [MAILTO]

4.12.3.3 Link type "bookmark"

The bookmark keyword may be used with a and area elements. This keyword creates a hyperlink.

4.12.3.4 Link type "help"

The help keyword may be used with link, a, and area elements. This keyword creates a hyperlink.

For a and area elements, the help keyword indicates that the referenced document provides further help information for the parent of the element defining the hyperlink, and its children.

For link elements, the help keyword indicates that the referenced document provides help for the page as a whole.

For a and area elements, on some browsers, the help keyword causes the link to use a different cursor.

4.12.3.5 Link type "icon"

The sizes attribute gives the sizes of icons for visual media. Its value, if present, is merely advisory. User agents may use the value to decide which icon(s) to use if multiple icons are available.

The any keyword represents that the resource contains a scalable icon, e.g. as provided by an SVG image.

The keywords specified on the sizes attribute must not represent icon sizes that are not actually available in the linked resource.

For historical reasons, the icon keyword may be preceded by the keyword "shortcut". If the "shortcut" keyword is present, it must be come immediately before the icon keyword and the two keywords must be separated by only a single U+0020 SPACE character.

4.12.3.6 Link type "license"

The license keyword may be used with link, a, and area elements. This keyword creates a hyperlink.

The license keyword indicates that the referenced document provides the copyright license terms under which the main content of the current document is provided.

This specification does not specify how to distinguish between the main content of a document and content that is not deemed to be part of that main content. The distinction should be made clear to the user.

4.12.3.7 Link type "nofollow"

The nofollow keyword may be used with a and area elements. This keyword does not create a hyperlink, but annotates any other hyperlinks created by the element (the implied hyperlink, if no other keywords create one).

The nofollow keyword indicates that the link is not endorsed by the original author or publisher of the page, or that the link to the referenced document was included primarily because of a commercial relationship between people affiliated with the two pages.

4.12.3.8 Link type "noreferrer"

The noreferrer keyword may be used with a and area elements. This keyword does not create a hyperlink, but annotates any other hyperlinks created by the element (the implied hyperlink, if no other keywords create one).

It indicates that no referrer information is to be leaked when following the link.

4.12.3.9 Link type "prefetch"

The prefetch keyword indicates that preemptively fetching and caching the specified resource is likely to be beneficial, as it is highly likely that the user will require this resource.

4.12.3.10 Link type "search"

The search keyword may be used with link, a, and area elements. This keyword creates a hyperlink.

The search keyword indicates that the referenced document provides an interface specifically for searching the document and its related resources.

OpenSearch description documents can be used with link elements and the search link type to enable user agents to autodiscover search interfaces. [OPENSEARCH]

4.12.3.11 Link type "stylesheet"

The specified resource is a resource that describes how to present the document. Exactly how the resource is to be processed depends on the actual type of the resource.

If the alternate keyword is also specified on the link element, then the link is an alternative stylesheet; in this case, the title attribute must be specified on the link element, with a non-empty value.

4.12.3.12 Link type "tag"

The tag keyword may be used with a and area elements. This keyword creates a hyperlink.

The tag keyword indicates that the tag that the referenced document represents applies to the current document.

Since it indicates that the tag applies to the current document, it would be inappropriate to use this keyword in the markup of a tag cloud, which lists the popular tags across a set of pages.

4.12.3.13 Sequential link types

A sequence of documents is one where each document can have a previous sibling and a next sibling. A document with no previous sibling is the start of its sequence, a document with no next sibling is the end of its sequence.

4.12.3.13.1 Link type "next"

The next keyword may be used with link, a, and area elements. This keyword creates a hyperlink.

The next keyword indicates that the document is part of a sequence, and that the link is leading to the document that is the next logical document in the sequence.

4.12.3.13.2 Link type "prev"

The prev keyword may be used with link, a, and area elements. This keyword creates a hyperlink.

The prev keyword indicates that the document is part of a sequence, and that the link is leading to the document that is the previous logical document in the sequence.

4.12.3.14 Other link types

Anyone is free to edit the microformats wiki existing-rel-values page at any time to add a type. Extension types must be specified with the following information:

Types defined as extensions in the microformats wiki existing-rel-values page with the status "proposed" or "ratified" may be used with the rel attribute on link, a, and area elements in accordance to the "Effect on..." field. [MFREL]

4.13 Common idioms without dedicated elements

4.13.1 The main part of the content

The main content of a page â€” not including headers and footers, navigation links, sidebars, advertisements, and so forth â€” can be marked up in a variety of ways, depending on the needs of the author.

The simplest solution is to not mark up the main content at all, and just leave it as implicit. Another way to think of this is that the body elements marks up the main content of the page, and the bits that aren't main content are excluded through the use of more appropriate elements like aside and nav.

If the main content is an independent unit of content that one could imagine syndicating independently, then the article element would be appropriate to mark up the main content of the document.

If the main content is not an independent unit of content so much as a section of a larger work, for instance a chapter, then the section element would be appropriate to mark up the main content of the document.

If neither article nor section would be appropriate, but the main content still needs an explicit element, for example for styling purposes, then the div element can be used.

4.13.2 Bread crumb navigation

This specification does not provide a machine-readable way of describing bread-crumb navigation menus. Authors are encouraged to just use a series of links in a paragraph. The nav element can be used to mark the section containing these paragraphs as being navigation blocks.

4.13.3 Tag clouds

This specification does not define any markup specifically for marking up lists of keywords that apply to a group of pages (also known as tag clouds). In general, authors are encouraged to either mark up such lists using ul elements with explicit inline counts that are then hidden and turned into a presentational effect using a style sheet, or to use SVG.

4.13.4 Conversations

This specification does not define a specific element for marking up conversations, meeting minutes, chat transcripts, dialogues in screenplays, instant message logs, and other situations where different players take turns in discourse.

Instead, authors are encouraged to mark up conversations using p elements and punctuation. Authors who need to mark the speaker for styling purposes are encouraged to use span or b. Paragraphs with their text wrapped in the i element can be used for marking up stage directions.

4.13.5 Footnotes

HTML does not have a dedicated mechanism for marking up footnotes. Here are the recommended alternatives.

For longer annotations, the a element should be used, pointing to an element later in the document. The convention is that the contents of the link be a number in square brackets.

For side notes, longer annotations that apply to entire sections of the text rather than just specific words or sentences, the aside element should be used.

For figures or tables, footnotes can be included in the relevant figcaption or caption element, or in surrounding prose.

5 Loading Web pages

5.1 Browsing contexts

A browsing context is an environment in which Document objects are presented to the user.

A tab or window in a Web browser typically contains a browsing context, as does an iframe.

In general, there is a 1-to-1 mapping from the Window object to the Document object. There are two exceptions. First, a Window can be reused for the presentation of a second Document in the same browsing context, such that the mapping is then 2-to-1. This occurs when a browsing context is navigated from the initial


about:blank

Document to another, with replacement enabled. Second, a Document can end up being reused for several Window objects when the document.open() method is used, such that the mapping is then 1-to-many.

A Document does not necessarily have a browsing context associated with it. In particular, data mining tools are likely to never instantiate browsing contexts.

5.1.1 Nested browsing contexts

Certain elements (for example, iframe elements) can instantiate further browsing contexts. These are called nested browsing contexts. If a browsing context P has a Document D with an element E that nests another browsing context C inside it, then C is said to be nested through D, and E is said to be the browsing context container of C. If the browsing context container element E is in the Document D, then P is said to be the parent browsing context of C and C is said to be a child browsing context of P. Otherwise, the nested browsing context C has no parent browsing context.

A browsing context A is said to be an ancestor of a browsing context B if there exists a browsing context A' that is a child browsing context of A and that is itself an ancestor of B, or if there is a browsing context P that is a child browsing context of A and that is the parent browsing context of B.

The list of the descendant browsing contexts of a Document d is the (ordered) list returned by the following algorithm:

5.1.1.1 Navigating nested browsing contexts in the DOM

5.1.2 Auxiliary browsing contexts

It is possible to create new browsing contexts that are related to a top-level browsing context without being nested through an element. Such browsing contexts are called auxiliary browsing contexts. Auxiliary browsing contexts are always top-level browsing contexts.

5.1.2.1 Navigating auxiliary browsing contexts in the DOM

5.1.3 Secondary browsing contexts

User agents may support secondary browsing contexts, which are browsing contexts that form part of the user agent's interface, apart from the main content area.

5.1.4 Browsing context names

Browsing contexts can have a browsing context name. By default, a browsing context has no name (its name is not set).

A valid browsing context name is any string with at least one character that does not start with a U+005F LOW LINE character. (Names starting with an underscore are reserved for special keywords.)

These values have different meanings based on whether the page is sandboxed or not, as summarized in the following (non-normative) table. In this table, "current" means the browsing context that the link or script is in, "parent" means the parent browsing context of the one the link or script is in, "master" means the nearest ancestor browsing context of the one the link or script is in that is not itself in a seamless iframe, "top" means the top-level browsing context of the one the link or script is in, "new" means a new top-level browsing context or auxiliary browsing context is to be created, subject to various user preferences and user agent policies, "maybe new" means the same as "new" but the requirements for those cases encourage user agents to treat it more like "none", and "none" means that by default nothing will happen.

Keyword	Ordinary effect	Effect in an `iframe` with...
none specified, for links and form submissions	current	master	current	master	current	master
none specified, for `window.open()`	new	new	maybe newâ€	maybe newâ€	maybe newâ€	maybe newâ€
empty string	current	master	current	master	current	master
`_blank`	new	new	maybe new	maybe new	maybe new	maybe new
`_self`	current	current	current	current	current	current
`_parent` if there isn't a parent	current	current	current	current	current	current
`_parent` if parent is also top	parent/top	parent/top	none	none	parent/top	parent/top
`_parent` if there is one and it's not top	parent	parent	none	none	none	none
`_top` if top is current	current	current	current	current	current	current
`_top` if top is not current	top	top	none	none	top	top
name that doesn't exist	new	new	maybe new	maybe new	maybe new	maybe new
name that exists and is a descendant	specified descendant	specified descendant	specified descendant	specified descendant	specified descendant	specified descendant
name that exists and is current	current	current	current	current	current	current
name that exists and is an ancestor that is top	specified ancestor	specified ancestor	none	none	specified ancestor/top	specified ancestor/top
name that exists and is an ancestor that is not top	specified ancestor	specified ancestor	none	none	none	none

â€ This case is only possible if the sandbox attribute also allows scripts.

5.2 The Window object

5.2.1 APIs for creating and navigating browsing contexts by name

5.2.2 Accessing other browsing contexts

5.2.3 Named access on the Window object

5.2.4 Browser interface elements

To allow Web pages to integrate with Web browsers, certain Web browser interface elements are exposed in a limited way to scripts in Web pages.

5.3 Origin

The origin of a resource and the effective script origin of a resource are both either opaque identifiers or tuples consisting of a scheme component, a host component, a port component, and optionally extra data.

The extra data could include the certificate of the site when using encrypted connections, to ensure that if the site's secure certificate changes, the origin is considered to change as well.

5.3.1 Relaxing the same-origin restriction

The domain attribute is used to enable pages on different hosts of a domain to access each others' DOMs.

Do not use the document.domain attribute when using shared hosting. If an untrusted third party is able to host an HTTP server at the same IP address but on a different port, then the same-origin protection that normally protects two different sites on the same host will fail, as the ports are ignored when comparing origins after the document.domain attribute has been used.

5.4 Session history and navigation

5.4.1 The session history of browsing contexts

The history attribute of the Window interface must return the object implementing the History interface for that Window object's Document.

Titles associated with session history entries need not have any relation with the current title of the Document. The title of a session history entry is intended to explain the state of the document at that point, so that the user can navigate the document's history.

URLs without associated state objects are added to the session history as the user (or script) navigates from page to page.

Pages can add state objects between their entry in the session history and the next ("forward") entry. These are then returned to the script when the user (or script) goes back in the history, thus enabling authors to use the "navigation" metaphor even in one-page applications.

At any point, one of the entries in the session history is the current entry. This is the entry representing the active document of the browsing context. The current entry is usually an entry for the location of the Document. However, it can also be one of the entries for state objects added to the history by that document.

An entry with persisted user state is one that also has user-agent defined state. This specification does not specify what kind of state can be stored.

For example, some user agents might want to persist the scroll position, or the values of form controls.

User agents that persist the value of form controls are encouraged to also persist their directionality (the value of the element's dir attribute). This prevents values from being displayed incorrectly after a history traversal when the user had originally entered the values with an explicit, non-default directionality.

Entries that consist of state objects share the same Document as the entry for the page that was active when they were added.

Contiguous entries that differ just by fragment identifier also share the same Document.

All entries that share the same Document (and that are therefore merely different states of one particular document) are contiguous by definition.

5.4.2 The History interface

The current entry of the joint session history is the entry that most recently became a current entry in its session history.

Entries in the joint session history are ordered chronologically by the time they were added to their respective session histories. (Since all these browsing contexts by definition share an event loop, there is always a well-defined sequential order in which their session histories had their entries added.) Each entry has an index; the earliest entry has index 0, and the subsequent entries are numbered with consecutively increasing integers (1, 2, 3, etc).

5.4.3 The Location interface

5.5 Browsing the Web

5.5.1 History traversal

The popstate event is fired in certain cases when navigating to a session history entry.

The hashchange event is fired when navigating to a session history entry whose URL differs from that of the previous one only in the fragment identifier.

5.5.2 Unloading documents

5.6 Offline Web applications

5.6.1 Introduction

In order to enable users to continue interacting with Web applications and documents even when their network connection is unavailable â€” for instance, because they are traveling outside of their ISP's coverage area â€” authors can provide a manifest which lists the files that are needed for the Web application to work offline and which causes the user's browser to keep a copy of the files for use offline.

To illustrate this, consider a simple clock applet consisting of an HTML page "clock.html", a CSS style sheet "clock.css", and a JavaScript script "clock.js".

If the user tries to open the "clock.html" page while offline, though, the user agent (unless it happens to have it still in the local cache) will fail with an error.

The author can instead provide a manifest of the three files, say "clock.appcache":

With a small change to the HTML file, the manifest (served as text/cache-manifest) is linked to the application:

Now, if the user goes to the page, the browser will cache the files and make them available even when the user is offline.

Authors are encouraged to include the main page in the manifest also, but in practice the page that referenced the manifest is automatically cached even if it isn't explicitly mentioned.

With the exception of "no-store" directive, HTTP cache headers and restrictions on caching pages served over TLS (encrypted, using https:) are overridden by manifests. Thus, pages will not expire from an application cache before the user agent has updated it, and even applications served over TLS can be made to work offline.

5.6.1.1 Event summary

When the user visits a page that declares a manifest, the browser will try to update the cache. It does this by fetching a copy of the manifest and, if the manifest has changed since the user agent last saw it, redownloading all the resources it mentions and caching them anew.

As this is going on, a number of events get fired on the ApplicationCache object to keep the script updated as to the state of the cache update, so that the user can be notified appropriately. The events are as follows:

Event name	Interface	Fired when...	Next events
`checking`	`Event`	The user agent is checking for an update, or attempting to download the manifest for the first time. This is always the first event in the sequence.	`noupdate`, `downloading`, `obsolete`, `error`
`noupdate`	`Event`	The manifest hadn't changed.	Last event in sequence.
`downloading`	`Event`	The user agent has found an update and is fetching it, or is downloading the resources listed by the manifest for the first time.	`progress`, `error`, `cached`, `updateready`
`progress`	`ProgressEvent`	The user agent is downloading resources listed by the manifest.	`progress`, `error`, `cached`, `updateready`
`cached`	`Event`	The resources listed in the manifest have been downloaded, and the application is now cached.	Last event in sequence.
`updateready`	`Event`	The resources listed in the manifest have been newly redownloaded, and the script can use `swapCache()` to switch to the new cache.	Last event in sequence.
`obsolete`	`Event`	The manifest was found to have become a 404 or 410 page, so the application cache is being deleted.	Last event in sequence.
`error`	`Event`	The manifest was a 404 or 410 page, so the attempt to cache the application has been aborted.	Last event in sequence.
The manifest hadn't changed, but the page referencing the manifest failed to download properly.
A fatal error occurred while fetching the resources listed in the manifest.
The manifest changed while the update was being run.	The user agent will try fetching the files again momentarily.

5.6.2 The cache manifest syntax

5.6.2.1 Some sample manifests

5.6.2.2 Writing cache manifests

An application cache manifest is a text file, whose text is encoded using UTF-8. Data in application cache manifests is line-based. Newlines must be represented by U+000A LINE FEED (LF) characters, U+000D CARRIAGE RETURN (CR) characters, or U+000D CARRIAGE RETURN (CR) U+000A LINE FEED (LF) pairs. [RFC3629]

This is a willful violation of RFC 2046, which requires all text/* types to only allow CRLF line breaks. This requirement, however, is outdated; the use of CR, LF, and CRLF line breaks is commonly supported and indeed sometimes CRLF is not supported by text editors. [RFC2046]

The first line of an application cache manifest must consist of the string "CACHE", a single U+0020 SPACE character, the string "MANIFEST", and either a U+0020 SPACE character, a U+0009 CHARACTER TABULATION (tab) character, a U+000A LINE FEED (LF) character, or a U+000D CARRIAGE RETURN (CR) character. The first line may optionally be preceded by a U+FEFF BYTE ORDER MARK (BOM) character. If any other text is found on the first line, it is ignored.

URLs that are to be fallback pages associated with fallback namespaces, and those namespaces themselves, must be given in fallback sections, with the namespace being the first URL of the data line, and the corresponding fallback page being the second URL. All the other pages to be cached must be listed in explicit sections.

Namespaces that the user agent is to put into the online whitelist must all be specified in online whitelist sections. (This is needed for any URL that the page is intending to use to communicate back to the server.) To specify that all URLs are automatically whitelisted in this way, a U+002A ASTERISK character (*) may be specified as one of the URLs.

Relative URLs must be given relative to the manifest's own URL. All URLs in the manifest must have the same <scheme> as the manifest itself (either explicitly or implicitly, through the use of relative URLs).

URLs in manifests must not have fragment identifiers (i.e. the U+0023 NUMBER SIGN character isn't allowed in URLs in manifests).

5.6.3 Application cache API

5.6.4 Browser state

This attribute is inherently unreliable. A computer can be connected to a network without having Internet access.

6 Web application APIs

6.1 Scripting

6.1.1 Introduction

Various mechanisms can cause author-provided executable code to run in the context of a document. These mechanisms include, but are probably not limited to:

6.1.2 Events

Many objects can have event handlers specified. These act as non-capture event listeners for the object on which they are specified. [DOMCORE]

Event handler content attributes, when specified, must contain valid JavaScript code which, when parsed, would match the FunctionBody production after automatic semicolon insertion. [ECMA262]

The Function interface represents a function in the scripting language being used. It is represented in Web IDL as follows:

The return value of the function affects whether the event is canceled or not: if the return value is false, the event is canceled (except for mouseover events, where the return value has to be true to cancel the event). With beforeunload events, the value is instead used to determine the message to show the user.

6.1.2.1 Event handlers on elements, Document objects, and Window objects

Event handler	Event handler event type
`onabort`	`abort`
`oncanplay`	`canplay`
`oncanplaythrough`	`canplaythrough`
`onchange`	`change`
`onclick`	`click`
`oncontextmenu`	`contextmenu`
`oncuechange`	`cuechange`
`ondblclick`	`dblclick`
`ondrag`	`drag`
`ondragend`	`dragend`
`ondragenter`	`dragenter`
`ondragleave`	`dragleave`
`ondragover`	`dragover`
`ondragstart`	`dragstart`
`ondrop`	`drop`
`ondurationchange`	`durationchange`
`onemptied`	`emptied`
`onended`	`ended`
`oninput`	`input`
`oninvalid`	`invalid`
`onkeydown`	`keydown`
`onkeypress`	`keypress`
`onkeyup`	`keyup`
`onloadeddata`	`loadeddata`
`onloadedmetadata`	`loadedmetadata`
`onloadstart`	`loadstart`
`onmousedown`	`mousedown`
`onmousemove`	`mousemove`
`onmouseout`	`mouseout`
`onmouseover`	`mouseover`
`onmouseup`	`mouseup`
`onmousewheel`	`mousewheel`
`onpause`	`pause`
`onplay`	`play`
`onplaying`	`playing`
`onprogress`	`progress`
`onratechange`	`ratechange`
`onreset`	`reset`
`onseeked`	`seeked`
`onseeking`	`seeking`
`onselect`	`select`
`onshow`	`show`
`onstalled`	`stalled`
`onsubmit`	`submit`
`onsuspend`	`suspend`
`ontimeupdate`	`timeupdate`
`onvolumechange`	`volumechange`
`onwaiting`	`waiting`

Event handler	Event handler event type
`onblur`	`blur`
`onerror`	`error`
`onfocus`	`focus`
`onload`	`load`
`onscroll`	`scroll`

The following are the event handlers (and their corresponding event handler event types) supported by Window objects, as IDL attributes on the Window object, and with corresponding content attributes and IDL attributes exposed on the body and


frameset

elements:

Event handler	Event handler event type
`onafterprint`	`afterprint`
`onbeforeprint`	`beforeprint`
`onbeforeunload`	`beforeunload`
`onblur`	`blur`
`onerror`	`error`
`onfocus`	`focus`
`onhashchange`	`hashchange`
`onload`	`load`
`onmessage`	`message`
`onoffline`	`offline`
`ononline`	`online`
`onpagehide`	`pagehide`
`onpageshow`	`pageshow`
`onpopstate`	`popstate`
`onresize`	`resize`
`onscroll`	`scroll`
`onstorage`	`storage`
`onunload`	`unload`

Event handler	Event handler event type
`onreadystatechange`	`readystatechange`

6.2 Base64 utility methods

The atob() and btoa() methods allow authors to transform content to and from the base64 encoding.

In these APIs, for mnemonic purposes, the "b" can be considered to stand for "binary", and the "a" for "ASCII". In practice, though, for primarily historical reasons, both the input and output of these functions are Unicode strings.

Some base64 encoders add newlines or other whitespace to their output. The atob() method throws an exception if its input contains characters other than those described by the regular expression bracket expression [+/=0-9A-Za-z], so other characters need to be removed before atob() is used for decoding.

6.3 Timers

This API does not guarantee that timers will run exactly on schedule. Delays due to CPU load, other tasks, etc, are to be expected.

6.4 User prompts

6.4.1 Simple dialogs

6.4.2 Printing

6.4.3 Dialogs implemented using separate documents

6.5 System state and capabilities

6.5.1 The Navigator object

6.5.1.1 Client identification

In certain cases, despite the best efforts of the entire industry, Web browsers have bugs and limitations that Web authors are forced to work around.

This section defines a collection of attributes that can be used to determine, from script, the kind of user agent in use, in order to work around these issues.

Client detection should always be limited to detecting known current versions; future versions and unknown versions should always be assumed to be fully compliant.

6.5.1.2 Custom scheme and content handlers

The registerProtocolHandler() method allows Web sites to register themselves as possible handlers for particular schemes. For example, an online telephone messaging service could register itself as a handler of the sms: scheme, so that if the user clicks on such a link, he is given the opportunity to use that Web site. Analogously, the registerContentHandler() method allows Web sites to register themselves as possible handlers for content in a particular MIME type. For example, the same online telephone messaging service could register itself as a handler for text/vcard files, so that if the user has no native application capable of handling vCards, his Web browser can instead suggest he use that site to view contact information stored on vCards that he opens. [RFC5724] RFC6350

In addition to the registration methods, there are also methods for determining if particular handlers have been registered, and for unregistering handlers.

6.5.1.3 Manually releasing the storage mutex

6.5.2 The External interface

The external attribute of the Window interface must return an instance of the External interface. The same object must be returned each time.

Another way of exposing search engines using OpenSearch description documents is using a link element with the search link type.

7 User interaction

7.1 The hidden attribute

All HTML elements may have the hidden content attribute set. The hidden attribute is a boolean attribute. When specified on an element, it indicates that the element is not yet, or is no longer, relevant.

The hidden attribute must not be used to hide content that could legitimately be shown in another presentation. For example, it is incorrect to use hidden to hide panels in a tabbed dialog, because the tabbed interface is merely a kind of overflow presentation â€” one could equally well just show all the form controls in one big page with a scrollbar. It is similarly incorrect to use this attribute to hide content just from one presentation â€” if something is marked hidden, it is hidden from all presentations, including, for instance, screen readers.

Elements that are not hidden should not link to or refer to elements that are hidden.

Elements in a section hidden by the hidden attribute are still active, e.g. scripts and form controls in such sections still execute and submit respectively. Only their presentation to the user changes.

7.2 Activation

7.3 Focus

7.3.1 Sequential focus navigation and the tabindex attribute

The tabindex content attribute specifies whether the element is focusable, whether it can be reached using sequential focus navigation, and the relative order of the element for the purposes of sequential focus navigation. The name "tab index" comes from the common use of the "tab" key to navigate through the focusable elements. The term "tabbing" refers to moving forward through the focusable elements that can be reached using sequential focus navigation.

The tabIndex IDL attribute must reflect the value of the tabindex content attribute. Its default value is 0 for elements that are focusable and âˆ’1 for elements that are not focusable.

7.3.2 Document-level focus APIs

7.3.3 Element-level focus APIs

7.4 Assigning keyboard shortcuts

7.4.1 Introduction

Each element that can be activated or focused can be assigned a single key combination to activate it, using the accesskey attribute.

The exact shortcut is determined by the user agent, based on information about the user's keyboard, what keyboard shortcuts already exist on the platform, and what other shortcuts have been specified on the page, using the information provided in the accesskey attribute as a guide.

In order to ensure that a relevant keyboard shortcut is available on a wide variety of input devices, the author can provide a number of alternatives in the accesskey attribute.

User agents can provide users with a list of the keyboard shortcuts, but authors are encouraged to do so also. The accessKeyLabel IDL attribute returns a string representing the actual key combination assigned by the user agent.

7.4.2 The accesskey attribute

All HTML elements may have the accesskey content attribute set. The accesskey attribute's value is used by the user agent as a guide for creating a keyboard shortcut that activates or focuses the element.

7.5 Editing

7.5.1 Making document regions editable: The contenteditable content attribute

The contenteditable attribute is an enumerated attribute whose keywords are the empty string, true, and false. The empty string and the true keyword map to the true state. The false keyword maps to the false state. In addition, there is a third state, the inherit state, which is the missing value default (and the invalid value default).

The true state indicates that the element is editable. The inherit state indicates that the element is editable if its parent is. The false state indicates that the element is not editable.

7.5.2 Making entire documents editable: The


designMode

IDL attribute

7.5.3 Best practices for in-page editors

Authors are encouraged to set the 'white-space' property on editing hosts and on markup that was originally created through these editing mechanisms to the value 'pre-wrap'. Default HTML whitespace handling is not well suited to WYSIWYG editing, and line wrapping will not work correctly in some corner cases if 'white-space' is left at its default value.

7.5.4 Editing APIs

The definition of the terms active range, editing host, and editable, the user interface requirements of elements that are editing hosts or editable, and the execCommand(), queryCommandEnabled(), queryCommandIndeterm(), queryCommandState(), queryCommandSupported(), and queryCommandValue() methods are defined in the HTML Editing APIs specification. Text selections are defined in the DOM Range specification. The interaction of editing and the undo/redo features in user agents is defined by the UndoManager and DOM Transaction specification. [EDITING] [DOMRANGE] [UNDO]

7.5.5 Spelling and grammar checking

The spellcheck attribute is an enumerated attribute whose keywords are the empty string, true and false. The empty string and the true keyword map to the true state. The false keyword maps to the false state. In addition, there is a third state, the default state, which is the missing value default (and the invalid value default).

The true state indicates that the element is to have its spelling and grammar checked. The default state indicates that the element is to act according to a default behavior, possibly based on the parent element's own spellcheck state, as defined below. The false state indicates that the element is not to be checked.

This specification does not define the user interface for spelling and grammar checkers. A user agent could offer on-demand checking, could perform continuous checking while the checking is enabled, or could use other interfaces.

7.6 Drag and drop

This specification does not define exactly what a drag-and-drop operation actually is.

On a visual medium with a pointing device, a drag operation could be the default action of a mousedown event that is followed by a series of mousemove events, and the drop could be triggered by the mouse being released.

When using an input modality other than a pointing device, users would probably have to explicitly indicate their intention to perform a drag-and-drop operation, stating what they wish to drag and where they wish to drop it, respectively.

7.6.1 Introduction

To make an element draggable is simple: give the element a draggable attribute, and set an event listener for dragstart that stores the data being dragged.

The event handler typically needs to check that it's not a text selection that is being dragged, and then needs to store data into the DataTransfer object and set the allowed effects (copy, move, link, or some combination).

To accept a drop, the drop target has to have a dropzone attribute and listen to the drop event.

The value of the dropzone attribute specifies what kind of data to accept (e.g. "string:text/plain" to accept any text strings, or "file:image/png" to accept a PNG image file) and what kind of feedback to give (e.g. "move" to indicate that the data will be moved).

Instead of using the dropzone attribute, a drop target can handle the dragenter event (to report whether or not the drop target is to accept the drop) and the dragover event (to specify what feedback is to be shown to the user).

The drop event allows the actual drop to be performed. This event needs to be canceled, so that the dropEffect attribute's value can be used by the source (otherwise it's reset).

To remove the original element (the one that was dragged) from the display, the dragend event can be used.

For our example here, that means updating the original markup to handle that event:

7.6.2 The drag data store

The data that underlies a drag-and-drop operation, known as the drag data store, consists of the following information:

7.6.3 The DataTransfer interface

7.6.3.1 The DataTransferItemList interface

7.6.3.2 The DataTransferItem interface

7.6.4 The DragEvent interface

The drag-and-drop processing model involves several events. They all use the DragEvent interface.

7.6.5 Events summary

Event Name	Target	Cancelable?	Drag data store mode	`dropEffect`	Default Action
`dragstart`	Source node	âœ“ Cancelable	Read/write mode	"`none`"	Initiate the drag-and-drop operation
`drag`	Source node	âœ“ Cancelable	Protected mode	"`none`"	Continue the drag-and-drop operation
`dragenter`	Immediate user selection or the body element	âœ“ Cancelable	Protected mode	Based on `effectAllowed` value	Reject immediate user selection as potential target element
`dragleave`	Previous target element	â€”	Protected mode	"`none`"	None
`dragover`	Current target element	âœ“ Cancelable	Protected mode	Based on `effectAllowed` value	Reset the current drag operation to "none"
`drop`	Current target element	âœ“ Cancelable	Read-only mode	Current drag operation	Varies
`dragend`	Source node	â€”	Protected mode	Current drag operation	Varies

Not shown in the above table: all these events bubble, and the effectAllowed attribute always has the value it had after the previous event was fired, defaulting to "uninitialized" in the dragstart event.

7.6.6 The draggable attribute

All HTML elements may have the draggable content attribute set. The draggable attribute is an enumerated attribute. It has three states. The first state is true and it has the keyword true. The second state is false and it has the keyword false. The third state is auto; it has no keywords but it is the missing value default.

The true state means the element is draggable; the false state means that it is not. The auto state uses the default behavior of the user agent.

7.6.7 The dropzone attribute

The dropzone content attribute's values must not have more than one of the three feedback values (copy, move, and link) specified. If none are specified, the copy value is implied.

The dropzone IDL attribute must reflect the content attribute of the same name.

8 The HTML syntax

This section only describes the rules for resources labeled with an HTML MIME type. Rules for XML resources are discussed in the section below entitled "The XHTML syntax".

8.1 Writing HTML documents

The various types of content mentioned above are described in the next few sections.

In addition, there are some restrictions on how character encoding declarations are to be serialized, as discussed in the section on that topic.

Many strings in the HTML syntax (e.g. the names of elements and their attributes) are case-insensitive, but only for characters in the ranges U+0041 to U+005A (LATIN CAPITAL LETTER A to LATIN CAPITAL LETTER Z) and U+0061 to U+007A (LATIN SMALL LETTER A to LATIN SMALL LETTER Z). For convenience, in this section this is just referred to as "case-insensitive".

8.1.1 The DOCTYPE

DOCTYPEs are required for legacy reasons. When omitted, browsers tend to use a different rendering mode that is incompatible with some specifications. Including the DOCTYPE in a document ensures that the browser makes a best-effort attempt at following the relevant specifications.

For the purposes of HTML generators that cannot output HTML markup with the short DOCTYPE "

<!DOCTYPE
html>

", a DOCTYPE legacy string may be inserted into the DOCTYPE (in the position defined above). This string must consist of:

In other words,

<!DOCTYPE html SYSTEM
"about:legacy-compat">

<!DOCTYPE html SYSTEM
'about:legacy-compat'>

, case-insensitively except for the part in single or double quotes.

The DOCTYPE legacy string should not be used unless the document is generated from a system that cannot output the shorter string.

To help authors transition from HTML4 and XHTML1, an obsolete permitted DOCTYPE string can be inserted into the DOCTYPE (in the position defined above). This string must consist of:

Allowed values for public and system identifiers in an obsolete permitted DOCTYPE string.
Public identifier	System identifier
`-//W3C//DTD HTML 4.0//EN`
`-//W3C//DTD HTML 4.0//EN`	`http://www.w3.org/TR/REC-html40/strict.dtd`
`-//W3C//DTD HTML 4.01//EN`
`-//W3C//DTD HTML 4.01//EN`	`http://www.w3.org/TR/html4/strict.dtd`
`-//W3C//DTD XHTML 1.0 Strict//EN`	`http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd`
`-//W3C//DTD XHTML 1.1//EN`	`http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd`

8.1.2 Elements

Tags are used to delimit the start and end of elements in the markup. Raw text, RCDATA, and normal elements have a start tag to indicate where they begin, and an end tag to indicate where they end. The start and end tags of certain normal elements can be omitted, as described later. Those that cannot be omitted must not be omitted. Void elements only have a start tag; end tags must not be specified for void elements. Foreign elements must either have a start tag and an end tag, or a start tag that is marked as self-closing, in which case they must not have an end tag.

The contents of the element must be placed between just after the start tag (which might be implied, in certain cases) and just before the end tag (which again, might be implied in certain cases). The exact allowed contents of each individual element depend on the content model of that element, as described earlier in this specification. Elements must not contain content that their content model disallows. In addition to the restrictions placed on the contents by those content models, however, the five types of elements have additional syntactic requirements.

Void elements can't have any contents (since there's no end tag, no content can be put between the start tag and the end tag).

Foreign elements whose start tag is marked as self-closing can't have any contents (since, again, as there's no end tag, no content can be put between the start tag and the end tag). Foreign elements whose start tag is not marked as self-closing can have text, character references, CDATA sections, other elements, and comments, but the text must not contain the character U+003C LESS-THAN SIGN (<) or an ambiguous ampersand.

Tags contain a tag name, giving the element's name. HTML elements all have names that only use characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), U+0061 LATIN SMALL LETTER A to U+007A LATIN SMALL LETTER Z, and U+0041 LATIN CAPITAL LETTER A to U+005A LATIN CAPITAL LETTER Z. In the HTML syntax, tag names, even those for foreign elements, may be written with any mix of lower- and uppercase letters that, when converted to all-lowercase, matches the element's tag name; tag names are case-insensitive.

8.1.2.1 Start tags

8.1.2.2 End tags

8.1.2.3 Attributes

Attributes have a name and a value. Attribute names must consist of one or more characters other than the space characters, U+0000 NULL, U+0022 QUOTATION MARK ("), U+0027 APOSTROPHE ('), U+003E GREATER-THAN SIGN (>), U+002F SOLIDUS (/), and U+003D EQUALS SIGN (=) characters, the control characters, and any characters that are not defined by Unicode. In the HTML syntax, attribute names, even those for foreign elements, may be written with any mix of lower- and uppercase letters that are an ASCII case-insensitive match for the attribute's name.

There must never be two or more attributes on the same start tag whose names are an ASCII case-insensitive match for each other.

When a foreign element has one of the namespaced attributes given by the local name and namespace of the first and second cells of a row from the following table, it must be written using the name given by the third cell from the same row.

Local name	Namespace	Attribute name
`actuate`	XLink namespace	`xlink:actuate`
`arcrole`	XLink namespace	`xlink:arcrole`
`href`	XLink namespace	`xlink:href`
`role`	XLink namespace	`xlink:role`
`show`	XLink namespace	`xlink:show`
`title`	XLink namespace	`xlink:title`
`type`	XLink namespace	`xlink:type`
`base`	XML namespace	`xml:base`
`lang`	XML namespace	`xml:lang`
`space`	XML namespace	`xml:space`
`xmlns`	XMLNS namespace	`xmlns`
`xlink`	XMLNS namespace	`xmlns:xlink`

8.1.2.4 Optional tags

Omitting an element's start tag in the situations described below does not mean the element is not present; it is implied, but it is still there. For example, an HTML document always has a root html element, even if the string <html> doesn't appear anywhere in the markup.

An html element's start tag may be omitted if the first thing inside the html element is not a comment.

An html element's end tag may be omitted if the html element is not immediately followed by a comment.

A head element's start tag may be omitted if the element is empty, or if the first thing inside the head element is an element.

A body element's start tag may be omitted if the element is empty, or if the first thing inside the body element is not a space character or a comment, except if the first thing inside the body element is a script or style element.

A body element's end tag may be omitted if the body element is not immediately followed by a comment.

An li element's end tag may be omitted if the li element is immediately followed by another li element or if there is no more content in the parent element.

A dt element's end tag may be omitted if the dt element is immediately followed by another dt element or a dd element.

A dd element's end tag may be omitted if the dd element is immediately followed by another dd element or a dt element, or if there is no more content in the parent element.

An rt element's end tag may be omitted if the rt element is immediately followed by an rt or rp element, or if there is no more content in the parent element.

An rp element's end tag may be omitted if the rp element is immediately followed by an rt or rp element, or if there is no more content in the parent element.

An optgroup element's end tag may be omitted if the optgroup element is immediately followed by another optgroup element, or if there is no more content in the parent element.

An option element's end tag may be omitted if the option element is immediately followed by another option element, or if it is immediately followed by an optgroup element, or if there is no more content in the parent element.

A colgroup element's start tag may be omitted if the first thing inside the colgroup element is a col element, and if the element is not immediately preceded by another colgroup element whose end tag has been omitted. (It can't be omitted if the element is empty.)

A thead element's end tag may be omitted if the thead element is immediately followed by a tbody or tfoot element.

A tbody element's start tag may be omitted if the first thing inside the tbody element is a tr element, and if the element is not immediately preceded by a tbody, thead, or tfoot element whose end tag has been omitted. (It can't be omitted if the element is empty.)

A tbody element's end tag may be omitted if the tbody element is immediately followed by a tbody or tfoot element, or if there is no more content in the parent element.

A tfoot element's end tag may be omitted if the tfoot element is immediately followed by a tbody element, or if there is no more content in the parent element.

A tr element's end tag may be omitted if the tr element is immediately followed by another tr element, or if there is no more content in the parent element.

A td element's end tag may be omitted if the td element is immediately followed by a td or th element, or if there is no more content in the parent element.

A th element's end tag may be omitted if the th element is immediately followed by a td or th element, or if there is no more content in the parent element.

8.1.2.5 Restrictions on content models

For historical reasons, certain elements have extra restrictions beyond even the restrictions given by their content model.

A table element must not contain tr elements, even though these elements are technically allowed inside table elements according to the content models described in this specification. (If a tr element is put inside a table in the markup, it will in fact imply a tbody start tag before it.)

A single newline may be placed immediately after the start tag of pre and textarea elements. This does not affect the processing of the element. The otherwise optional newline must be included if the element's contents themselves start with a newline (because otherwise the leading newline in the contents would be treated like the optional newline, and ignored).

8.1.2.6 Restrictions on the contents of raw text and RCDATA elements

The text in raw text and RCDATA elements must not contain any occurrences of the string "</" (U+003C LESS-THAN SIGN, U+002F SOLIDUS) followed by characters that case-insensitively match the tag name of the element followed by one of U+0009 CHARACTER TABULATION (tab), U+000A LINE FEED (LF), U+000C FORM FEED (FF), U+000D CARRIAGE RETURN (CR), U+0020 SPACE, U+003E GREATER-THAN SIGN (>), or U+002F SOLIDUS (/).

8.1.3 Text

Text is allowed inside elements, attribute values, and comments. Text must consist of Unicode characters. Text must not contain U+0000 characters. Text must not contain permanently undefined Unicode characters (noncharacters). Text must not contain control characters other than space characters. Extra constraints are placed on what is and what is not allowed in text based on where the text is to be put, as described in the other sections.

8.1.3.1 Newlines

Newlines in HTML may be represented either as U+000D CARRIAGE RETURN (CR) characters, U+000A LINE FEED (LF) characters, or pairs of U+000D CARRIAGE RETURN (CR), U+000A LINE FEED (LF) characters in that order.

Where character references are allowed, a character reference of a U+000A LINE FEED (LF) character (but not a U+000D CARRIAGE RETURN (CR) character) also represents a newline.

8.1.4 Character references

In certain cases described in other sections, text may be mixed with character references. These can be used to escape characters that couldn't otherwise legally be included in text.

Character references must start with a U+0026 AMPERSAND character (&). Following this, there are three possible kinds of character references:

The numeric character reference forms described above are allowed to reference any Unicode code point other than U+0000, U+000D, permanently undefined Unicode characters (noncharacters), and control characters other than space characters.

An ambiguous ampersand is a U+0026 AMPERSAND character (&) that is followed by one or more characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), U+0061 LATIN SMALL LETTER A to U+007A LATIN SMALL LETTER Z, and U+0041 LATIN CAPITAL LETTER A to U+005A LATIN CAPITAL LETTER Z, followed by a U+003B SEMICOLON character (;), where these characters do not match any of the names given in the named character references section.

8.1.5 CDATA sections

8.1.6 Comments

Comments must start with the four character sequence U+003C LESS-THAN SIGN, U+0021 EXCLAMATION MARK, U+002D HYPHEN-MINUS, U+002D HYPHEN-MINUS ().

8.2 Named character references

This table lists the character reference names that are supported by HTML, and the code points to which they refer. It is referenced by the previous sections.

Name	Character(s)	Glyph
`Aacute;`	U+000C1	Ã
`aacute;`	U+000E1	Ã¡
`Abreve;`	U+00102	Ä‚
`abreve;`	U+00103	Äƒ
`ac;`	U+0223E	âˆ¾
`acd;`	U+0223F	âˆ¿
`acE;`	U+0223E U+00333	âˆ¾Ì³
`Acirc;`	U+000C2	Ã‚
`acirc;`	U+000E2	Ã¢
`acute;`	U+000B4	Â´
`Acy;`	U+00410	Ð
`acy;`	U+00430	Ð°
`AElig;`	U+000C6	Ã†
`aelig;`	U+000E6	Ã¦
`af;`	U+02061	â¡
`Afr;`	U+1D504	ð”„
`afr;`	U+1D51E	ð”ž
`Agrave;`	U+000C0	Ã€
`agrave;`	U+000E0	Ã
`alefsym;`	U+02135	â„µ
`aleph;`	U+02135	â„µ
`Alpha;`	U+00391	Î‘
`alpha;`	U+003B1	Î±
`Amacr;`	U+00100	Ä€
`amacr;`	U+00101	Ä
`amalg;`	U+02A3F	â¨¿
`AMP;`	U+00026	&
`amp;`	U+00026	&
`And;`	U+02A53	â©“
`and;`	U+02227	âˆ§
`andand;`	U+02A55	â©•
`andd;`	U+02A5C	â©œ
`andslope;`	U+02A58	â©˜
`andv;`	U+02A5A	â©š
`ang;`	U+02220	âˆ
`ange;`	U+029A4	â¦¤
`angle;`	U+02220	âˆ
`angmsd;`	U+02221	âˆ¡
`angmsdaa;`	U+029A8	â¦¨
`angmsdab;`	U+029A9	â¦©
`angmsdac;`	U+029AA	â¦ª
`angmsdad;`	U+029AB	â¦«
`angmsdae;`	U+029AC	â¦¬
`angmsdaf;`	U+029AD	â¦
`angmsdag;`	U+029AE	â¦®
`angmsdah;`	U+029AF	â¦¯
`angrt;`	U+0221F	âˆŸ
`angrtvb;`	U+022BE	âŠ¾
`angrtvbd;`	U+0299D	â¦
`angsph;`	U+02222	âˆ¢
`angst;`	U+000C5	Ã…
`angzarr;`	U+0237C	â¼
`Aogon;`	U+00104	Ä„
`aogon;`	U+00105	Ä…
`Aopf;`	U+1D538	ð”¸
`aopf;`	U+1D552	ð•’
`ap;`	U+02248	â‰ˆ
`apacir;`	U+02A6F	â©¯
`apE;`	U+02A70	â©°
`ape;`	U+0224A	â‰Š
`apid;`	U+0224B	â‰‹
`apos;`	U+00027	'
`ApplyFunction;`	U+02061	â¡
`approx;`	U+02248	â‰ˆ
`approxeq;`	U+0224A	â‰Š
`Aring;`	U+000C5	Ã…
`aring;`	U+000E5	Ã¥
`Ascr;`	U+1D49C	ð’œ
`ascr;`	U+1D4B6	ð’¶
`Assign;`	U+02254	â‰”
`ast;`	U+0002A	*
`asymp;`	U+02248	â‰ˆ
`asympeq;`	U+0224D	â‰
`Atilde;`	U+000C3	Ãƒ
`atilde;`	U+000E3	Ã£
`Auml;`	U+000C4	Ã„
`auml;`	U+000E4	Ã¤
`awconint;`	U+02233	âˆ³
`awint;`	U+02A11	â¨‘
`backcong;`	U+0224C	â‰Œ
`backepsilon;`	U+003F6	Ï¶
`backprime;`	U+02035	â€µ
`backsim;`	U+0223D	âˆ½
`backsimeq;`	U+022CD	â‹
`Backslash;`	U+02216	âˆ–
`Barv;`	U+02AE7	â«§
`barvee;`	U+022BD	âŠ½
`Barwed;`	U+02306	âŒ†
`barwed;`	U+02305	âŒ…
`barwedge;`	U+02305	âŒ…
`bbrk;`	U+023B5	âŽµ
`bbrktbrk;`	U+023B6	âŽ¶
`bcong;`	U+0224C	â‰Œ
`Bcy;`	U+00411	Ð‘
`bcy;`	U+00431	Ð±
`bdquo;`	U+0201E	â€ž
`becaus;`	U+02235	âˆµ
`Because;`	U+02235	âˆµ
`because;`	U+02235	âˆµ
`bemptyv;`	U+029B0	â¦°
`bepsi;`	U+003F6	Ï¶
`bernou;`	U+0212C	â„¬
`Bernoullis;`	U+0212C	â„¬
`Beta;`	U+00392	Î’
`beta;`	U+003B2	Î²
`beth;`	U+02136	â„¶
`between;`	U+0226C	â‰¬
`Bfr;`	U+1D505	ð”…
`bfr;`	U+1D51F	ð”Ÿ
`bigcap;`	U+022C2	â‹‚
`bigcirc;`	U+025EF	â—¯
`bigcup;`	U+022C3	â‹ƒ
`bigodot;`	U+02A00	â¨€
`bigoplus;`	U+02A01	â¨
`bigotimes;`	U+02A02	â¨‚
`bigsqcup;`	U+02A06	â¨†
`bigstar;`	U+02605	â˜…
`bigtriangledown;`	U+025BD	â–½
`bigtriangleup;`	U+025B3	â–³
`biguplus;`	U+02A04	â¨„
`bigvee;`	U+022C1	â‹
`bigwedge;`	U+022C0	â‹€
`bkarow;`	U+0290D	â¤
`blacklozenge;`	U+029EB	â§«
`blacksquare;`	U+025AA	â–ª
`blacktriangle;`	U+025B4	â–´
`blacktriangledown;`	U+025BE	â–¾
`blacktriangleleft;`	U+025C2	â—‚
`blacktriangleright;`	U+025B8	â–¸
`blank;`	U+02423	â£
`blk12;`	U+02592	â–’
`blk14;`	U+02591	â–‘
`blk34;`	U+02593	â–“
`block;`	U+02588	â–ˆ
`bne;`	U+0003D U+020E5	=âƒ¥
`bnequiv;`	U+02261 U+020E5	â‰¡âƒ¥
`bNot;`	U+02AED	â«
`bnot;`	U+02310	âŒ
`Bopf;`	U+1D539	ð”¹
`bopf;`	U+1D553	ð•“
`bot;`	U+022A5	âŠ¥
`bottom;`	U+022A5	âŠ¥
`bowtie;`	U+022C8	â‹ˆ
`boxbox;`	U+029C9	â§‰
`boxDL;`	U+02557	â•—
`boxDl;`	U+02556	â•–
`boxdL;`	U+02555	â••
`boxdl;`	U+02510	â”
`boxDR;`	U+02554	â•”
`boxDr;`	U+02553	â•“
`boxdR;`	U+02552	â•’
`boxdr;`	U+0250C	â”Œ
`boxH;`	U+02550	â•
`boxh;`	U+02500	â”€
`boxHD;`	U+02566	â•¦
`boxHd;`	U+02564	â•¤
`boxhD;`	U+02565	â•¥
`boxhd;`	U+0252C	â”¬
`boxHU;`	U+02569	â•©
`boxHu;`	U+02567	â•§
`boxhU;`	U+02568	â•¨
`boxhu;`	U+02534	â”´
`boxminus;`	U+0229F	âŠŸ
`boxplus;`	U+0229E	âŠž
`boxtimes;`	U+022A0	âŠ
`boxUL;`	U+0255D	â•
`boxUl;`	U+0255C	â•œ
`boxuL;`	U+0255B	â•›
`boxul;`	U+02518	â”˜
`boxUR;`	U+0255A	â•š
`boxUr;`	U+02559	â•™
`boxuR;`	U+02558	â•˜
`boxur;`	U+02514	â””
`boxV;`	U+02551	â•‘
`boxv;`	U+02502	â”‚
`boxVH;`	U+0256C	â•¬
`boxVh;`	U+0256B	â•«
`boxvH;`	U+0256A	â•ª
`boxvh;`	U+0253C	â”¼
`boxVL;`	U+02563	â•£
`boxVl;`	U+02562	â•¢
`boxvL;`	U+02561	â•¡
`boxvl;`	U+02524	â”¤
`boxVR;`	U+02560	â•
`boxVr;`	U+0255F	â•Ÿ
`boxvR;`	U+0255E	â•ž
`boxvr;`	U+0251C	â”œ
`bprime;`	U+02035	â€µ
`Breve;`	U+002D8	Ë˜
`breve;`	U+002D8	Ë˜
`brvbar;`	U+000A6	Â¦
`Bscr;`	U+0212C	â„¬
`bscr;`	U+1D4B7	ð’·
`bsemi;`	U+0204F	â
`bsim;`	U+0223D	âˆ½
`bsime;`	U+022CD	â‹
`bsol;`	U+0005C	\
`bsolb;`	U+029C5	â§…
`bsolhsub;`	U+027C8	âŸˆ
`bull;`	U+02022	â€¢
`bullet;`	U+02022	â€¢
`bump;`	U+0224E	â‰Ž
`bumpE;`	U+02AAE	âª®
`bumpe;`	U+0224F	â‰
`Bumpeq;`	U+0224E	â‰Ž
`bumpeq;`	U+0224F	â‰
`Cacute;`	U+00106	Ä†
`cacute;`	U+00107	Ä‡
`Cap;`	U+022D2	â‹’
`cap;`	U+02229	âˆ©
`capand;`	U+02A44	â©„
`capbrcup;`	U+02A49	â©‰
`capcap;`	U+02A4B	â©‹
`capcup;`	U+02A47	â©‡
`capdot;`	U+02A40	â©€
`CapitalDifferentialD;`	U+02145	â……
`caps;`	U+02229 U+0FE00	âˆ©ï¸€
`caret;`	U+02041	â
`caron;`	U+002C7	Ë‡
`Cayleys;`	U+0212D	â„
`ccaps;`	U+02A4D	â©
`Ccaron;`	U+0010C	ÄŒ
`ccaron;`	U+0010D	Ä
`Ccedil;`	U+000C7	Ã‡
`ccedil;`	U+000E7	Ã§
`Ccirc;`	U+00108	Äˆ
`ccirc;`	U+00109	Ä‰
`Cconint;`	U+02230	âˆ°
`ccups;`	U+02A4C	â©Œ
`ccupssm;`	U+02A50	â©
`Cdot;`	U+0010A	ÄŠ
`cdot;`	U+0010B	Ä‹
`cedil;`	U+000B8	Â¸
`Cedilla;`	U+000B8	Â¸
`cemptyv;`	U+029B2	â¦²
`cent;`	U+000A2	Â¢
`CenterDot;`	U+000B7	Â·
`centerdot;`	U+000B7	Â·
`Cfr;`	U+0212D	â„
`cfr;`	U+1D520	ð”
`CHcy;`	U+00427	Ð§
`chcy;`	U+00447	Ñ‡
`check;`	U+02713	âœ“
`checkmark;`	U+02713	âœ“
`Chi;`	U+003A7	Î§
`chi;`	U+003C7	Ï‡
`cir;`	U+025CB	â—‹
`circ;`	U+002C6	Ë†
`circeq;`	U+02257	â‰—
`circlearrowleft;`	U+021BA	â†º
`circlearrowright;`	U+021BB	â†»
`circledast;`	U+0229B	âŠ›
`circledcirc;`	U+0229A	âŠš
`circleddash;`	U+0229D	âŠ
`CircleDot;`	U+02299	âŠ™
`circledR;`	U+000AE	Â®
`circledS;`	U+024C8	â“ˆ
`CircleMinus;`	U+02296	âŠ–
`CirclePlus;`	U+02295	âŠ•
`CircleTimes;`	U+02297	âŠ—
`cirE;`	U+029C3	â§ƒ
`cire;`	U+02257	â‰—
`cirfnint;`	U+02A10	â¨
`cirmid;`	U+02AEF	â«¯
`cirscir;`	U+029C2	â§‚
`ClockwiseContourIntegral;`	U+02232	âˆ²
`CloseCurlyDoubleQuote;`	U+0201D	â€
`CloseCurlyQuote;`	U+02019	â€™
`clubs;`	U+02663	â™£
`clubsuit;`	U+02663	â™£
`Colon;`	U+02237	âˆ·
`colon;`	U+0003A	:
`Colone;`	U+02A74	â©´
`colone;`	U+02254	â‰”
`coloneq;`	U+02254	â‰”
`comma;`	U+0002C	,
`commat;`	U+00040	@
`comp;`	U+02201	âˆ
`compfn;`	U+02218	âˆ˜
`complement;`	U+02201	âˆ
`complexes;`	U+02102	â„‚
`cong;`	U+02245	â‰…
`congdot;`	U+02A6D	â©
`Congruent;`	U+02261	â‰¡
`Conint;`	U+0222F	âˆ¯
`conint;`	U+0222E	âˆ®
`ContourIntegral;`	U+0222E	âˆ®
`Copf;`	U+02102	â„‚
`copf;`	U+1D554	ð•”
`coprod;`	U+02210	âˆ
`Coproduct;`	U+02210	âˆ
`COPY;`	U+000A9	Â©
`copy;`	U+000A9	Â©
`copysr;`	U+02117	â„—
`CounterClockwiseContourIntegral;`	U+02233	âˆ³
`crarr;`	U+021B5	â†µ
`Cross;`	U+02A2F	â¨¯
`cross;`	U+02717	âœ—
`Cscr;`	U+1D49E	ð’ž
`cscr;`	U+1D4B8	ð’¸
`csub;`	U+02ACF	â«
`csube;`	U+02AD1	â«‘
`csup;`	U+02AD0	â«
`csupe;`	U+02AD2	â«’
`ctdot;`	U+022EF	â‹¯
`cudarrl;`	U+02938	â¤¸
`cudarrr;`	U+02935	â¤µ
`cuepr;`	U+022DE	â‹ž
`cuesc;`	U+022DF	â‹Ÿ
`cularr;`	U+021B6	â†¶
`cularrp;`	U+0293D	â¤½
`Cup;`	U+022D3	â‹“
`cup;`	U+0222A	âˆª
`cupbrcap;`	U+02A48	â©ˆ
`CupCap;`	U+0224D	â‰
`cupcap;`	U+02A46	â©†
`cupcup;`	U+02A4A	â©Š
`cupdot;`	U+0228D	âŠ
`cupor;`	U+02A45	â©…
`cups;`	U+0222A U+0FE00	âˆªï¸€
`curarr;`	U+021B7	â†·
`curarrm;`	U+0293C	â¤¼
`curlyeqprec;`	U+022DE	â‹ž
`curlyeqsucc;`	U+022DF	â‹Ÿ
`curlyvee;`	U+022CE	â‹Ž
`curlywedge;`	U+022CF	â‹
`curren;`	U+000A4	Â¤
`curvearrowleft;`	U+021B6	â†¶
`curvearrowright;`	U+021B7	â†·
`cuvee;`	U+022CE	â‹Ž
`cuwed;`	U+022CF	â‹
`cwconint;`	U+02232	âˆ²
`cwint;`	U+02231	âˆ±
`cylcty;`	U+0232D	âŒ
`Dagger;`	U+02021	â€¡
`dagger;`	U+02020	â€
`daleth;`	U+02138	â„¸
`Darr;`	U+021A1	â†¡
`dArr;`	U+021D3	â‡“
`darr;`	U+02193	â†“
`dash;`	U+02010	â€
`Dashv;`	U+02AE4	â«¤
`dashv;`	U+022A3	âŠ£
`dbkarow;`	U+0290F	â¤
`dblac;`	U+002DD	Ë
`Dcaron;`	U+0010E	ÄŽ
`dcaron;`	U+0010F	Ä
`Dcy;`	U+00414	Ð”
`dcy;`	U+00434	Ð´
`DD;`	U+02145	â……
`dd;`	U+02146	â…†
`ddagger;`	U+02021	â€¡
`ddarr;`	U+021CA	â‡Š
`DDotrahd;`	U+02911	â¤‘
`ddotseq;`	U+02A77	â©·
`deg;`	U+000B0	Â°
`Del;`	U+02207	âˆ‡
`Delta;`	U+00394	Î”
`delta;`	U+003B4	Î´
`demptyv;`	U+029B1	â¦±
`dfisht;`	U+0297F	â¥¿
`Dfr;`	U+1D507	ð”‡
`dfr;`	U+1D521	ð”¡
`dHar;`	U+02965	â¥¥
`dharl;`	U+021C3	â‡ƒ
`dharr;`	U+021C2	â‡‚
`DiacriticalAcute;`	U+000B4	Â´
`DiacriticalDot;`	U+002D9	Ë™
`DiacriticalDoubleAcute;`	U+002DD	Ë
`DiacriticalGrave;`	U+00060	`
`DiacriticalTilde;`	U+002DC	Ëœ
`diam;`	U+022C4	â‹„
`Diamond;`	U+022C4	â‹„
`diamond;`	U+022C4	â‹„
`diamondsuit;`	U+02666	â™¦
`diams;`	U+02666	â™¦
`die;`	U+000A8	Â¨
`DifferentialD;`	U+02146	â…†
`digamma;`	U+003DD	Ï
`disin;`	U+022F2	â‹²
`div;`	U+000F7	Ã·
`divide;`	U+000F7	Ã·
`divideontimes;`	U+022C7	â‹‡
`divonx;`	U+022C7	â‹‡
`DJcy;`	U+00402	Ð‚
`djcy;`	U+00452	Ñ’
`dlcorn;`	U+0231E	âŒž
`dlcrop;`	U+0230D	âŒ
`dollar;`	U+00024	$
`Dopf;`	U+1D53B	ð”»
`dopf;`	U+1D555	ð••
`Dot;`	U+000A8	Â¨
`dot;`	U+002D9	Ë™
`DotDot;`	U+020DC	â—Œâƒœ
`doteq;`	U+02250	â‰
`doteqdot;`	U+02251	â‰‘
`DotEqual;`	U+02250	â‰
`dotminus;`	U+02238	âˆ¸
`dotplus;`	U+02214	âˆ”
`dotsquare;`	U+022A1	âŠ¡
`doublebarwedge;`	U+02306	âŒ†
`DoubleContourIntegral;`	U+0222F	âˆ¯
`DoubleDot;`	U+000A8	Â¨
`DoubleDownArrow;`	U+021D3	â‡“
`DoubleLeftArrow;`	U+021D0	â‡
`DoubleLeftRightArrow;`	U+021D4	â‡”
`DoubleLeftTee;`	U+02AE4	â«¤
`DoubleLongLeftArrow;`	U+027F8	âŸ¸
`DoubleLongLeftRightArrow;`	U+027FA	âŸº
`DoubleLongRightArrow;`	U+027F9	âŸ¹
`DoubleRightArrow;`	U+021D2	â‡’
`DoubleRightTee;`	U+022A8	âŠ¨
`DoubleUpArrow;`	U+021D1	â‡‘
`DoubleUpDownArrow;`	U+021D5	â‡•
`DoubleVerticalBar;`	U+02225	âˆ¥
`DownArrow;`	U+02193	â†“
`Downarrow;`	U+021D3	â‡“
`downarrow;`	U+02193	â†“
`DownArrowBar;`	U+02913	â¤“
`DownArrowUpArrow;`	U+021F5	â‡µ
`DownBreve;`	U+00311	â—ŒÌ‘
`downdownarrows;`	U+021CA	â‡Š
`downharpoonleft;`	U+021C3	â‡ƒ
`downharpoonright;`	U+021C2	â‡‚
`DownLeftRightVector;`	U+02950	â¥
`DownLeftTeeVector;`	U+0295E	â¥ž
`DownLeftVector;`	U+021BD	â†½
`DownLeftVectorBar;`	U+02956	â¥–
`DownRightTeeVector;`	U+0295F	â¥Ÿ
`DownRightVector;`	U+021C1	â‡
`DownRightVectorBar;`	U+02957	â¥—
`DownTee;`	U+022A4	âŠ¤
`DownTeeArrow;`	U+021A7	â†§
`drbkarow;`	U+02910	â¤
`drcorn;`	U+0231F	âŒŸ
`drcrop;`	U+0230C	âŒŒ
`Dscr;`	U+1D49F	ð’Ÿ
`dscr;`	U+1D4B9	ð’¹
`DScy;`	U+00405	Ð…
`dscy;`	U+00455	Ñ•
`dsol;`	U+029F6	â§¶
`Dstrok;`	U+00110	Ä
`dstrok;`	U+00111	Ä‘
`dtdot;`	U+022F1	â‹±
`dtri;`	U+025BF	â–¿
`dtrif;`	U+025BE	â–¾
`duarr;`	U+021F5	â‡µ
`duhar;`	U+0296F	â¥¯
`dwangle;`	U+029A6	â¦¦
`DZcy;`	U+0040F	Ð
`dzcy;`	U+0045F	ÑŸ
`dzigrarr;`	U+027FF	âŸ¿
`Eacute;`	U+000C9	Ã‰
`eacute;`	U+000E9	Ã©
`easter;`	U+02A6E	â©®
`Ecaron;`	U+0011A	Äš
`ecaron;`	U+0011B	Ä›
`ecir;`	U+02256	â‰–
`Ecirc;`	U+000CA	ÃŠ
`ecirc;`	U+000EA	Ãª
`ecolon;`	U+02255	â‰•
`Ecy;`	U+0042D	Ð
`ecy;`	U+0044D	Ñ
`eDDot;`	U+02A77	â©·
`Edot;`	U+00116	Ä–
`eDot;`	U+02251	â‰‘
`edot;`	U+00117	Ä—
`ee;`	U+02147	â…‡
`efDot;`	U+02252	â‰’
`Efr;`	U+1D508	ð”ˆ
`efr;`	U+1D522	ð”¢
`eg;`	U+02A9A	âªš
`Egrave;`	U+000C8	Ãˆ
`egrave;`	U+000E8	Ã¨
`egs;`	U+02A96	âª–
`egsdot;`	U+02A98	âª˜
`el;`	U+02A99	âª™
`Element;`	U+02208	âˆˆ
`elinters;`	U+023E7	â§
`ell;`	U+02113	â„“
`els;`	U+02A95	âª•
`elsdot;`	U+02A97	âª—
`Emacr;`	U+00112	Ä’
`emacr;`	U+00113	Ä“
`empty;`	U+02205	âˆ…
`emptyset;`	U+02205	âˆ…
`EmptySmallSquare;`	U+025FB	â—»
`emptyv;`	U+02205	âˆ…
`EmptyVerySmallSquare;`	U+025AB	â–«
`emsp;`	U+02003	â€ƒ
`emsp13;`	U+02004	â€„
`emsp14;`	U+02005	â€…
`ENG;`	U+0014A	ÅŠ
`eng;`	U+0014B	Å‹
`ensp;`	U+02002	â€‚
`Eogon;`	U+00118	Ä˜
`eogon;`	U+00119	Ä™
`Eopf;`	U+1D53C	ð”¼
`eopf;`	U+1D556	ð•–
`epar;`	U+022D5	â‹•
`eparsl;`	U+029E3	â§£
`eplus;`	U+02A71	â©±
`epsi;`	U+003B5	Îµ
`Epsilon;`	U+00395	Î•
`epsilon;`	U+003B5	Îµ
`epsiv;`	U+003F5	Ïµ
`eqcirc;`	U+02256	â‰–
`eqcolon;`	U+02255	â‰•
`eqsim;`	U+02242	â‰‚
`eqslantgtr;`	U+02A96	âª–
`eqslantless;`	U+02A95	âª•
`Equal;`	U+02A75	â©µ
`equals;`	U+0003D	=
`EqualTilde;`	U+02242	â‰‚
`equest;`	U+0225F	â‰Ÿ
`Equilibrium;`	U+021CC	â‡Œ
`equiv;`	U+02261	â‰¡
`equivDD;`	U+02A78	â©¸
`eqvparsl;`	U+029E5	â§¥
`erarr;`	U+02971	â¥±
`erDot;`	U+02253	â‰“
`Escr;`	U+02130	â„°
`escr;`	U+0212F	â„¯
`esdot;`	U+02250	â‰
`Esim;`	U+02A73	â©³
`esim;`	U+02242	â‰‚
`Eta;`	U+00397	Î—
`eta;`	U+003B7	Î·
`ETH;`	U+000D0	Ã
`eth;`	U+000F0	Ã°
`Euml;`	U+000CB	Ã‹
`euml;`	U+000EB	Ã«
`euro;`	U+020AC	â‚¬
`excl;`	U+00021	!
`exist;`	U+02203	âˆƒ
`Exists;`	U+02203	âˆƒ
`expectation;`	U+02130	â„°
`ExponentialE;`	U+02147	â…‡
`exponentiale;`	U+02147	â…‡
`fallingdotseq;`	U+02252	â‰’
`Fcy;`	U+00424	Ð¤
`fcy;`	U+00444	Ñ„
`female;`	U+02640	â™€
`ffilig;`	U+0FB03	ï¬ƒ
`fflig;`	U+0FB00	ï¬€
`ffllig;`	U+0FB04	ï¬„
`Ffr;`	U+1D509	ð”‰
`ffr;`	U+1D523	ð”£
`filig;`	U+0FB01	ï¬
`FilledSmallSquare;`	U+025FC	â—¼
`FilledVerySmallSquare;`	U+025AA	â–ª
`fjlig;`	U+00066 U+0006A	fj
`flat;`	U+0266D	â™
`fllig;`	U+0FB02	ï¬‚
`fltns;`	U+025B1	â–±
`fnof;`	U+00192	Æ’
`Fopf;`	U+1D53D	ð”½
`fopf;`	U+1D557	ð•—
`ForAll;`	U+02200	âˆ€
`forall;`	U+02200	âˆ€
`fork;`	U+022D4	â‹”
`forkv;`	U+02AD9	â«™
`Fouriertrf;`	U+02131	â„±
`fpartint;`	U+02A0D	â¨
`frac12;`	U+000BD	Â½
`frac13;`	U+02153	â…“
`frac14;`	U+000BC	Â¼
`frac15;`	U+02155	â…•
`frac16;`	U+02159	â…™
`frac18;`	U+0215B	â…›
`frac23;`	U+02154	â…”
`frac25;`	U+02156	â…–
`frac34;`	U+000BE	Â¾
`frac35;`	U+02157	â…—
`frac38;`	U+0215C	â…œ
`frac45;`	U+02158	â…˜
`frac56;`	U+0215A	â…š
`frac58;`	U+0215D	â…
`frac78;`	U+0215E	â…ž
`frasl;`	U+02044	â„
`frown;`	U+02322	âŒ¢
`Fscr;`	U+02131	â„±
`fscr;`	U+1D4BB	ð’»
`gacute;`	U+001F5	Çµ
`Gamma;`	U+00393	Î“
`gamma;`	U+003B3	Î³
`Gammad;`	U+003DC	Ïœ
`gammad;`	U+003DD	Ï
`gap;`	U+02A86	âª†
`Gbreve;`	U+0011E	Äž
`gbreve;`	U+0011F	ÄŸ
`Gcedil;`	U+00122	Ä¢
`Gcirc;`	U+0011C	Äœ
`gcirc;`	U+0011D	Ä
`Gcy;`	U+00413	Ð“
`gcy;`	U+00433	Ð³
`Gdot;`	U+00120	Ä
`gdot;`	U+00121	Ä¡
`gE;`	U+02267	â‰§
`ge;`	U+02265	â‰¥
`gEl;`	U+02A8C	âªŒ
`gel;`	U+022DB	â‹›
`geq;`	U+02265	â‰¥
`geqq;`	U+02267	â‰§
`geqslant;`	U+02A7E	â©¾
`ges;`	U+02A7E	â©¾
`gescc;`	U+02AA9	âª©
`gesdot;`	U+02A80	âª€
`gesdoto;`	U+02A82	âª‚
`gesdotol;`	U+02A84	âª„
`gesl;`	U+022DB U+0FE00	â‹›ï¸€
`gesles;`	U+02A94	âª”
`Gfr;`	U+1D50A	ð”Š
`gfr;`	U+1D524	ð”¤
`Gg;`	U+022D9	â‹™
`gg;`	U+0226B	â‰«
`ggg;`	U+022D9	â‹™
`gimel;`	U+02137	â„·
`GJcy;`	U+00403	Ðƒ
`gjcy;`	U+00453	Ñ“
`gl;`	U+02277	â‰·
`gla;`	U+02AA5	âª¥
`glE;`	U+02A92	âª’
`glj;`	U+02AA4	âª¤
`gnap;`	U+02A8A	âªŠ
`gnapprox;`	U+02A8A	âªŠ
`gnE;`	U+02269	â‰©
`gne;`	U+02A88	âªˆ
`gneq;`	U+02A88	âªˆ
`gneqq;`	U+02269	â‰©
`gnsim;`	U+022E7	â‹§
`Gopf;`	U+1D53E	ð”¾
`gopf;`	U+1D558	ð•˜
`grave;`	U+00060	`
`GreaterEqual;`	U+02265	â‰¥
`GreaterEqualLess;`	U+022DB	â‹›
`GreaterFullEqual;`	U+02267	â‰§
`GreaterGreater;`	U+02AA2	âª¢
`GreaterLess;`	U+02277	â‰·
`GreaterSlantEqual;`	U+02A7E	â©¾
`GreaterTilde;`	U+02273	â‰³
`Gscr;`	U+1D4A2	ð’¢
`gscr;`	U+0210A	â„Š
`gsim;`	U+02273	â‰³
`gsime;`	U+02A8E	âªŽ
`gsiml;`	U+02A90	âª
`GT;`	U+0003E	>
`Gt;`	U+0226B	â‰«
`gt;`	U+0003E	>
`gtcc;`	U+02AA7	âª§
`gtcir;`	U+02A7A	â©º
`gtdot;`	U+022D7	â‹—
`gtlPar;`	U+02995	â¦•
`gtquest;`	U+02A7C	â©¼
`gtrapprox;`	U+02A86	âª†
`gtrarr;`	U+02978	â¥¸
`gtrdot;`	U+022D7	â‹—
`gtreqless;`	U+022DB	â‹›
`gtreqqless;`	U+02A8C	âªŒ
`gtrless;`	U+02277	â‰·
`gtrsim;`	U+02273	â‰³
`gvertneqq;`	U+02269 U+0FE00	â‰©ï¸€
`gvnE;`	U+02269 U+0FE00	â‰©ï¸€
`Hacek;`	U+002C7	Ë‡
`hairsp;`	U+0200A	â€Š
`half;`	U+000BD	Â½
`hamilt;`	U+0210B	â„‹
`HARDcy;`	U+0042A	Ðª
`hardcy;`	U+0044A	ÑŠ
`hArr;`	U+021D4	â‡”
`harr;`	U+02194	â†”
`harrcir;`	U+02948	â¥ˆ
`harrw;`	U+021AD	â†
`Hat;`	U+0005E	^
`hbar;`	U+0210F	â„
`Hcirc;`	U+00124	Ä¤
`hcirc;`	U+00125	Ä¥
`hearts;`	U+02665	â™¥
`heartsuit;`	U+02665	â™¥
`hellip;`	U+02026	â€¦
`hercon;`	U+022B9	âŠ¹
`Hfr;`	U+0210C	â„Œ
`hfr;`	U+1D525	ð”¥
`HilbertSpace;`	U+0210B	â„‹
`hksearow;`	U+02925	â¤¥
`hkswarow;`	U+02926	â¤¦
`hoarr;`	U+021FF	â‡¿
`homtht;`	U+0223B	âˆ»
`hookleftarrow;`	U+021A9	â†©
`hookrightarrow;`	U+021AA	â†ª
`Hopf;`	U+0210D	â„
`hopf;`	U+1D559	ð•™
`horbar;`	U+02015	â€•
`HorizontalLine;`	U+02500	â”€
`Hscr;`	U+0210B	â„‹
`hscr;`	U+1D4BD	ð’½
`hslash;`	U+0210F	â„
`Hstrok;`	U+00126	Ä¦
`hstrok;`	U+00127	Ä§
`HumpDownHump;`	U+0224E	â‰Ž
`HumpEqual;`	U+0224F	â‰
`hybull;`	U+02043	âƒ
`hyphen;`	U+02010	â€
`Iacute;`	U+000CD	Ã
`iacute;`	U+000ED	Ã
`ic;`	U+02063	â£
`Icirc;`	U+000CE	ÃŽ
`icirc;`	U+000EE	Ã®
`Icy;`	U+00418	Ð˜
`icy;`	U+00438	Ð¸
`Idot;`	U+00130	Ä°
`IEcy;`	U+00415	Ð•
`iecy;`	U+00435	Ðµ
`iexcl;`	U+000A1	Â¡
`iff;`	U+021D4	â‡”
`Ifr;`	U+02111	â„‘
`ifr;`	U+1D526	ð”¦
`Igrave;`	U+000CC	ÃŒ
`igrave;`	U+000EC	Ã¬
`ii;`	U+02148	â…ˆ
`iiiint;`	U+02A0C	â¨Œ
`iiint;`	U+0222D	âˆ
`iinfin;`	U+029DC	â§œ
`iiota;`	U+02129	â„©
`IJlig;`	U+00132	Ä²
`ijlig;`	U+00133	Ä³
`Im;`	U+02111	â„‘
`Imacr;`	U+0012A	Äª
`imacr;`	U+0012B	Ä«
`image;`	U+02111	â„‘
`ImaginaryI;`	U+02148	â…ˆ
`imagline;`	U+02110	â„
`imagpart;`	U+02111	â„‘
`imath;`	U+00131	Ä±
`imof;`	U+022B7	âŠ·
`imped;`	U+001B5	Æµ
`Implies;`	U+021D2	â‡’
`in;`	U+02208	âˆˆ
`incare;`	U+02105	â„…
`infin;`	U+0221E	âˆž
`infintie;`	U+029DD	â§
`inodot;`	U+00131	Ä±
`Int;`	U+0222C	âˆ¬
`int;`	U+0222B	âˆ«
`intcal;`	U+022BA	âŠº
`integers;`	U+02124	â„¤
`Integral;`	U+0222B	âˆ«
`intercal;`	U+022BA	âŠº
`Intersection;`	U+022C2	â‹‚
`intlarhk;`	U+02A17	â¨—
`intprod;`	U+02A3C	â¨¼
`InvisibleComma;`	U+02063	â£
`InvisibleTimes;`	U+02062	â¢
`IOcy;`	U+00401	Ð
`iocy;`	U+00451	Ñ‘
`Iogon;`	U+0012E	Ä®
`iogon;`	U+0012F	Ä¯
`Iopf;`	U+1D540	ð•€
`iopf;`	U+1D55A	ð•š
`Iota;`	U+00399	Î™
`iota;`	U+003B9	Î¹
`iprod;`	U+02A3C	â¨¼
`iquest;`	U+000BF	Â¿
`Iscr;`	U+02110	â„
`iscr;`	U+1D4BE	ð’¾
`isin;`	U+02208	âˆˆ
`isindot;`	U+022F5	â‹µ
`isinE;`	U+022F9	â‹¹
`isins;`	U+022F4	â‹´
`isinsv;`	U+022F3	â‹³
`isinv;`	U+02208	âˆˆ
`it;`	U+02062	â¢
`Itilde;`	U+00128	Ä¨
`itilde;`	U+00129	Ä©
`Iukcy;`	U+00406	Ð†
`iukcy;`	U+00456	Ñ–
`Iuml;`	U+000CF	Ã
`iuml;`	U+000EF	Ã¯
`Jcirc;`	U+00134	Ä´
`jcirc;`	U+00135	Äµ
`Jcy;`	U+00419	Ð™
`jcy;`	U+00439	Ð¹
`Jfr;`	U+1D50D	ð”
`jfr;`	U+1D527	ð”§
`jmath;`	U+00237	È·
`Jopf;`	U+1D541	ð•
`jopf;`	U+1D55B	ð•›
`Jscr;`	U+1D4A5	ð’¥
`jscr;`	U+1D4BF	ð’¿
`Jsercy;`	U+00408	Ðˆ
`jsercy;`	U+00458	Ñ˜
`Jukcy;`	U+00404	Ð„
`jukcy;`	U+00454	Ñ”
`Kappa;`	U+0039A	Îš
`kappa;`	U+003BA	Îº
`kappav;`	U+003F0	Ï°
`Kcedil;`	U+00136	Ä¶
`kcedil;`	U+00137	Ä·
`Kcy;`	U+0041A	Ðš
`kcy;`	U+0043A	Ðº
`Kfr;`	U+1D50E	ð”Ž
`kfr;`	U+1D528	ð”¨
`kgreen;`	U+00138	Ä¸
`KHcy;`	U+00425	Ð¥
`khcy;`	U+00445	Ñ…
`KJcy;`	U+0040C	ÐŒ
`kjcy;`	U+0045C	Ñœ
`Kopf;`	U+1D542	ð•‚
`kopf;`	U+1D55C	ð•œ
`Kscr;`	U+1D4A6	ð’¦
`kscr;`	U+1D4C0	ð“€
`lAarr;`	U+021DA	â‡š
`Lacute;`	U+00139	Ä¹
`lacute;`	U+0013A	Äº
`laemptyv;`	U+029B4	â¦´
`lagran;`	U+02112	â„’
`Lambda;`	U+0039B	Î›
`lambda;`	U+003BB	Î»
`Lang;`	U+027EA	âŸª
`lang;`	U+027E8	âŸ¨
`langd;`	U+02991	â¦‘
`langle;`	U+027E8	âŸ¨
`lap;`	U+02A85	âª…
`Laplacetrf;`	U+02112	â„’
`laquo;`	U+000AB	Â«
`Larr;`	U+0219E	â†ž
`lArr;`	U+021D0	â‡
`larr;`	U+02190	â†
`larrb;`	U+021E4	â‡¤
`larrbfs;`	U+0291F	â¤Ÿ
`larrfs;`	U+0291D	â¤
`larrhk;`	U+021A9	â†©
`larrlp;`	U+021AB	â†«
`larrpl;`	U+02939	â¤¹
`larrsim;`	U+02973	â¥³
`larrtl;`	U+021A2	â†¢
`lat;`	U+02AAB	âª«
`lAtail;`	U+0291B	â¤›
`latail;`	U+02919	â¤™
`late;`	U+02AAD	âª
`lates;`	U+02AAD U+0FE00	âªï¸€
`lBarr;`	U+0290E	â¤Ž
`lbarr;`	U+0290C	â¤Œ
`lbbrk;`	U+02772	â²
`lbrace;`	U+0007B	{
`lbrack;`	U+0005B	[
`lbrke;`	U+0298B	â¦‹
`lbrksld;`	U+0298F	â¦
`lbrkslu;`	U+0298D	â¦
`Lcaron;`	U+0013D	Ä½
`lcaron;`	U+0013E	Ä¾
`Lcedil;`	U+0013B	Ä»
`lcedil;`	U+0013C	Ä¼
`lceil;`	U+02308	âŒˆ
`lcub;`	U+0007B	{
`Lcy;`	U+0041B	Ð›
`lcy;`	U+0043B	Ð»
`ldca;`	U+02936	â¤¶
`ldquo;`	U+0201C	â€œ
`ldquor;`	U+0201E	â€ž
`ldrdhar;`	U+02967	â¥§
`ldrushar;`	U+0294B	â¥‹
`ldsh;`	U+021B2	â†²
`lE;`	U+02266	â‰¦
`le;`	U+02264	â‰¤
`LeftAngleBracket;`	U+027E8	âŸ¨
`LeftArrow;`	U+02190	â†
`Leftarrow;`	U+021D0	â‡
`leftarrow;`	U+02190	â†
`LeftArrowBar;`	U+021E4	â‡¤
`LeftArrowRightArrow;`	U+021C6	â‡†
`leftarrowtail;`	U+021A2	â†¢
`LeftCeiling;`	U+02308	âŒˆ
`LeftDoubleBracket;`	U+027E6	âŸ¦
`LeftDownTeeVector;`	U+02961	â¥¡
`LeftDownVector;`	U+021C3	â‡ƒ
`LeftDownVectorBar;`	U+02959	â¥™
`LeftFloor;`	U+0230A	âŒŠ
`leftharpoondown;`	U+021BD	â†½
`leftharpoonup;`	U+021BC	â†¼
`leftleftarrows;`	U+021C7	â‡‡
`LeftRightArrow;`	U+02194	â†”
`Leftrightarrow;`	U+021D4	â‡”
`leftrightarrow;`	U+02194	â†”
`leftrightarrows;`	U+021C6	â‡†
`leftrightharpoons;`	U+021CB	â‡‹
`leftrightsquigarrow;`	U+021AD	â†
`LeftRightVector;`	U+0294E	â¥Ž
`LeftTee;`	U+022A3	âŠ£
`LeftTeeArrow;`	U+021A4	â†¤
`LeftTeeVector;`	U+0295A	â¥š
`leftthreetimes;`	U+022CB	â‹‹
`LeftTriangle;`	U+022B2	âŠ²
`LeftTriangleBar;`	U+029CF	â§
`LeftTriangleEqual;`	U+022B4	âŠ´
`LeftUpDownVector;`	U+02951	â¥‘
`LeftUpTeeVector;`	U+02960	â¥
`LeftUpVector;`	U+021BF	â†¿
`LeftUpVectorBar;`	U+02958	â¥˜
`LeftVector;`	U+021BC	â†¼
`LeftVectorBar;`	U+02952	â¥’
`lEg;`	U+02A8B	âª‹
`leg;`	U+022DA	â‹š
`leq;`	U+02264	â‰¤
`leqq;`	U+02266	â‰¦
`leqslant;`	U+02A7D	â©½
`les;`	U+02A7D	â©½
`lescc;`	U+02AA8	âª¨
`lesdot;`	U+02A7F	â©¿
`lesdoto;`	U+02A81	âª
`lesdotor;`	U+02A83	âªƒ
`lesg;`	U+022DA U+0FE00	â‹šï¸€
`lesges;`	U+02A93	âª“
`lessapprox;`	U+02A85	âª…
`lessdot;`	U+022D6	â‹–
`lesseqgtr;`	U+022DA	â‹š
`lesseqqgtr;`	U+02A8B	âª‹
`LessEqualGreater;`	U+022DA	â‹š
`LessFullEqual;`	U+02266	â‰¦
`LessGreater;`	U+02276	â‰¶
`lessgtr;`	U+02276	â‰¶
`LessLess;`	U+02AA1	âª¡
`lesssim;`	U+02272	â‰²
`LessSlantEqual;`	U+02A7D	â©½
`LessTilde;`	U+02272	â‰²
`lfisht;`	U+0297C	â¥¼
`lfloor;`	U+0230A	âŒŠ
`Lfr;`	U+1D50F	ð”
`lfr;`	U+1D529	ð”©
`lg;`	U+02276	â‰¶
`lgE;`	U+02A91	âª‘
`lHar;`	U+02962	â¥¢
`lhard;`	U+021BD	â†½
`lharu;`	U+021BC	â†¼
`lharul;`	U+0296A	â¥ª
`lhblk;`	U+02584	â–„
`LJcy;`	U+00409	Ð‰
`ljcy;`	U+00459	Ñ™
`Ll;`	U+022D8	â‹˜
`ll;`	U+0226A	â‰ª
`llarr;`	U+021C7	â‡‡
`llcorner;`	U+0231E	âŒž
`Lleftarrow;`	U+021DA	â‡š
`llhard;`	U+0296B	â¥«
`lltri;`	U+025FA	â—º
`Lmidot;`	U+0013F	Ä¿
`lmidot;`	U+00140	Å€
`lmoust;`	U+023B0	âŽ°
`lmoustache;`	U+023B0	âŽ°
`lnap;`	U+02A89	âª‰
`lnapprox;`	U+02A89	âª‰
`lnE;`	U+02268	â‰¨
`lne;`	U+02A87	âª‡
`lneq;`	U+02A87	âª‡
`lneqq;`	U+02268	â‰¨
`lnsim;`	U+022E6	â‹¦
`loang;`	U+027EC	âŸ¬
`loarr;`	U+021FD	â‡½
`lobrk;`	U+027E6	âŸ¦
`LongLeftArrow;`	U+027F5	âŸµ
`Longleftarrow;`	U+027F8	âŸ¸
`longleftarrow;`	U+027F5	âŸµ
`LongLeftRightArrow;`	U+027F7	âŸ·
`Longleftrightarrow;`	U+027FA	âŸº
`longleftrightarrow;`	U+027F7	âŸ·
`longmapsto;`	U+027FC	âŸ¼
`LongRightArrow;`	U+027F6	âŸ¶
`Longrightarrow;`	U+027F9	âŸ¹
`longrightarrow;`	U+027F6	âŸ¶
`looparrowleft;`	U+021AB	â†«
`looparrowright;`	U+021AC	â†¬
`lopar;`	U+02985	â¦…
`Lopf;`	U+1D543	ð•ƒ
`lopf;`	U+1D55D	ð•
`loplus;`	U+02A2D	â¨
`lotimes;`	U+02A34	â¨´
`lowast;`	U+02217	âˆ—
`lowbar;`	U+0005F	_
`LowerLeftArrow;`	U+02199	â†™
`LowerRightArrow;`	U+02198	â†˜
`loz;`	U+025CA	â—Š
`lozenge;`	U+025CA	â—Š
`lozf;`	U+029EB	â§«
`lpar;`	U+00028	(
`lparlt;`	U+02993	â¦“
`lrarr;`	U+021C6	â‡†
`lrcorner;`	U+0231F	âŒŸ
`lrhar;`	U+021CB	â‡‹
`lrhard;`	U+0296D	â¥
`lrm;`	U+0200E	â€Ž
`lrtri;`	U+022BF	âŠ¿
`lsaquo;`	U+02039	â€¹
`Lscr;`	U+02112	â„’
`lscr;`	U+1D4C1	ð“
`Lsh;`	U+021B0	â†°
`lsh;`	U+021B0	â†°
`lsim;`	U+02272	â‰²
`lsime;`	U+02A8D	âª
`lsimg;`	U+02A8F	âª
`lsqb;`	U+0005B	[
`lsquo;`	U+02018	â€˜
`lsquor;`	U+0201A	â€š
`Lstrok;`	U+00141	Å
`lstrok;`	U+00142	Å‚
`LT;`	U+0003C	<
`Lt;`	U+0226A	â‰ª
`lt;`	U+0003C	<
`ltcc;`	U+02AA6	âª¦
`ltcir;`	U+02A79	â©¹
`ltdot;`	U+022D6	â‹–
`lthree;`	U+022CB	â‹‹
`ltimes;`	U+022C9	â‹‰
`ltlarr;`	U+02976	â¥¶
`ltquest;`	U+02A7B	â©»
`ltri;`	U+025C3	â—ƒ
`ltrie;`	U+022B4	âŠ´
`ltrif;`	U+025C2	â—‚
`ltrPar;`	U+02996	â¦–
`lurdshar;`	U+0294A	â¥Š
`luruhar;`	U+02966	â¥¦
`lvertneqq;`	U+02268 U+0FE00	â‰¨ï¸€
`lvnE;`	U+02268 U+0FE00	â‰¨ï¸€
`macr;`	U+000AF	Â¯
`male;`	U+02642	â™‚
`malt;`	U+02720	âœ
`maltese;`	U+02720	âœ
`Map;`	U+02905	â¤…
`map;`	U+021A6	â†¦
`mapsto;`	U+021A6	â†¦
`mapstodown;`	U+021A7	â†§
`mapstoleft;`	U+021A4	â†¤
`mapstoup;`	U+021A5	â†¥
`marker;`	U+025AE	â–®
`mcomma;`	U+02A29	â¨©
`Mcy;`	U+0041C	Ðœ
`mcy;`	U+0043C	Ð¼
`mdash;`	U+02014	â€”
`mDDot;`	U+0223A	âˆº
`measuredangle;`	U+02221	âˆ¡
`MediumSpace;`	U+0205F	âŸ
`Mellintrf;`	U+02133	â„³
`Mfr;`	U+1D510	ð”
`mfr;`	U+1D52A	ð”ª
`mho;`	U+02127	â„§
`micro;`	U+000B5	Âµ
`mid;`	U+02223	âˆ£
`midast;`	U+0002A	*
`midcir;`	U+02AF0	â«°
`middot;`	U+000B7	Â·
`minus;`	U+02212	âˆ’
`minusb;`	U+0229F	âŠŸ
`minusd;`	U+02238	âˆ¸
`minusdu;`	U+02A2A	â¨ª
`MinusPlus;`	U+02213	âˆ“
`mlcp;`	U+02ADB	â«›
`mldr;`	U+02026	â€¦
`mnplus;`	U+02213	âˆ“
`models;`	U+022A7	âŠ§
`Mopf;`	U+1D544	ð•„
`mopf;`	U+1D55E	ð•ž
`mp;`	U+02213	âˆ“
`Mscr;`	U+02133	â„³
`mscr;`	U+1D4C2	ð“‚
`mstpos;`	U+0223E	âˆ¾
`Mu;`	U+0039C	Îœ
`mu;`	U+003BC	Î¼
`multimap;`	U+022B8	âŠ¸
`mumap;`	U+022B8	âŠ¸
`nabla;`	U+02207	âˆ‡
`Nacute;`	U+00143	Åƒ
`nacute;`	U+00144	Å„
`nang;`	U+02220 U+020D2	âˆ âƒ’
`nap;`	U+02249	â‰‰
`napE;`	U+02A70 U+00338	â©°Ì¸
`napid;`	U+0224B U+00338	â‰‹Ì¸
`napos;`	U+00149	Å‰
`napprox;`	U+02249	â‰‰
`natur;`	U+0266E	â™®
`natural;`	U+0266E	â™®
`naturals;`	U+02115	â„•
`nbsp;`	U+000A0
`nbump;`	U+0224E U+00338	â‰ŽÌ¸
`nbumpe;`	U+0224F U+00338	â‰Ì¸
`ncap;`	U+02A43	â©ƒ
`Ncaron;`	U+00147	Å‡
`ncaron;`	U+00148	Åˆ
`Ncedil;`	U+00145	Å…
`ncedil;`	U+00146	Å†
`ncong;`	U+02247	â‰‡
`ncongdot;`	U+02A6D U+00338	â©Ì¸
`ncup;`	U+02A42	â©‚
`Ncy;`	U+0041D	Ð
`ncy;`	U+0043D	Ð½
`ndash;`	U+02013	â€“
`ne;`	U+02260	â‰
`nearhk;`	U+02924	â¤¤
`neArr;`	U+021D7	â‡—
`nearr;`	U+02197	â†—
`nearrow;`	U+02197	â†—
`nedot;`	U+02250 U+00338	â‰Ì¸
`NegativeMediumSpace;`	U+0200B	â€‹
`NegativeThickSpace;`	U+0200B	â€‹
`NegativeThinSpace;`	U+0200B	â€‹
`NegativeVeryThinSpace;`	U+0200B	â€‹
`nequiv;`	U+02262	â‰¢
`nesear;`	U+02928	â¤¨
`nesim;`	U+02242 U+00338	â‰‚Ì¸
`NestedGreaterGreater;`	U+0226B	â‰«
`NestedLessLess;`	U+0226A	â‰ª
`NewLine;`	U+0000A	âŠ
`nexist;`	U+02204	âˆ„
`nexists;`	U+02204	âˆ„
`Nfr;`	U+1D511	ð”‘
`nfr;`	U+1D52B	ð”«
`ngE;`	U+02267 U+00338	â‰§Ì¸
`nge;`	U+02271	â‰±
`ngeq;`	U+02271	â‰±
`ngeqq;`	U+02267 U+00338	â‰§Ì¸
`ngeqslant;`	U+02A7E U+00338	â©¾Ì¸
`nges;`	U+02A7E U+00338	â©¾Ì¸
`nGg;`	U+022D9 U+00338	â‹™Ì¸
`ngsim;`	U+02275	â‰µ
`nGt;`	U+0226B U+020D2	â‰«âƒ’
`ngt;`	U+0226F	â‰¯
`ngtr;`	U+0226F	â‰¯
`nGtv;`	U+0226B U+00338	â‰«Ì¸
`nhArr;`	U+021CE	â‡Ž
`nharr;`	U+021AE	â†®
`nhpar;`	U+02AF2	â«²
`ni;`	U+0220B	âˆ‹
`nis;`	U+022FC	â‹¼
`nisd;`	U+022FA	â‹º
`niv;`	U+0220B	âˆ‹
`NJcy;`	U+0040A	ÐŠ
`njcy;`	U+0045A	Ñš
`nlArr;`	U+021CD	â‡
`nlarr;`	U+0219A	â†š
`nldr;`	U+02025	â€¥
`nlE;`	U+02266 U+00338	â‰¦Ì¸
`nle;`	U+02270	â‰°
`nLeftarrow;`	U+021CD	â‡
`nleftarrow;`	U+0219A	â†š
`nLeftrightarrow;`	U+021CE	â‡Ž
`nleftrightarrow;`	U+021AE	â†®
`nleq;`	U+02270	â‰°
`nleqq;`	U+02266 U+00338	â‰¦Ì¸
`nleqslant;`	U+02A7D U+00338	â©½Ì¸
`nles;`	U+02A7D U+00338	â©½Ì¸
`nless;`	U+0226E	â‰®
`nLl;`	U+022D8 U+00338	â‹˜Ì¸
`nlsim;`	U+02274	â‰´
`nLt;`	U+0226A U+020D2	â‰ªâƒ’
`nlt;`	U+0226E	â‰®
`nltri;`	U+022EA	â‹ª
`nltrie;`	U+022EC	â‹¬
`nLtv;`	U+0226A U+00338	â‰ªÌ¸
`nmid;`	U+02224	âˆ¤
`NoBreak;`	U+02060	â
`NonBreakingSpace;`	U+000A0
`Nopf;`	U+02115	â„•
`nopf;`	U+1D55F	ð•Ÿ
`Not;`	U+02AEC	â«¬
`not;`	U+000AC	Â¬
`NotCongruent;`	U+02262	â‰¢
`NotCupCap;`	U+0226D	â‰
`NotDoubleVerticalBar;`	U+02226	âˆ¦
`NotElement;`	U+02209	âˆ‰
`NotEqual;`	U+02260	â‰
`NotEqualTilde;`	U+02242 U+00338	â‰‚Ì¸
`NotExists;`	U+02204	âˆ„
`NotGreater;`	U+0226F	â‰¯
`NotGreaterEqual;`	U+02271	â‰±
`NotGreaterFullEqual;`	U+02267 U+00338	â‰§Ì¸
`NotGreaterGreater;`	U+0226B U+00338	â‰«Ì¸
`NotGreaterLess;`	U+02279	â‰¹
`NotGreaterSlantEqual;`	U+02A7E U+00338	â©¾Ì¸
`NotGreaterTilde;`	U+02275	â‰µ
`NotHumpDownHump;`	U+0224E U+00338	â‰ŽÌ¸
`NotHumpEqual;`	U+0224F U+00338	â‰Ì¸
`notin;`	U+02209	âˆ‰
`notindot;`	U+022F5 U+00338	â‹µÌ¸
`notinE;`	U+022F9 U+00338	â‹¹Ì¸
`notinva;`	U+02209	âˆ‰
`notinvb;`	U+022F7	â‹·
`notinvc;`	U+022F6	â‹¶
`NotLeftTriangle;`	U+022EA	â‹ª
`NotLeftTriangleBar;`	U+029CF U+00338	â§Ì¸
`NotLeftTriangleEqual;`	U+022EC	â‹¬
`NotLess;`	U+0226E	â‰®
`NotLessEqual;`	U+02270	â‰°
`NotLessGreater;`	U+02278	â‰¸
`NotLessLess;`	U+0226A U+00338	â‰ªÌ¸
`NotLessSlantEqual;`	U+02A7D U+00338	â©½Ì¸
`NotLessTilde;`	U+02274	â‰´
`NotNestedGreaterGreater;`	U+02AA2 U+00338	âª¢Ì¸
`NotNestedLessLess;`	U+02AA1 U+00338	âª¡Ì¸
`notni;`	U+0220C	âˆŒ
`notniva;`	U+0220C	âˆŒ
`notnivb;`	U+022FE	â‹¾
`notnivc;`	U+022FD	â‹½
`NotPrecedes;`	U+02280	âŠ€
`NotPrecedesEqual;`	U+02AAF U+00338	âª¯Ì¸
`NotPrecedesSlantEqual;`	U+022E0	â‹
`NotReverseElement;`	U+0220C	âˆŒ
`NotRightTriangle;`	U+022EB	â‹«
`NotRightTriangleBar;`	U+029D0 U+00338	â§Ì¸
`NotRightTriangleEqual;`	U+022ED	â‹
`NotSquareSubset;`	U+0228F U+00338	âŠÌ¸
`NotSquareSubsetEqual;`	U+022E2	â‹¢
`NotSquareSuperset;`	U+02290 U+00338	âŠÌ¸
`NotSquareSupersetEqual;`	U+022E3	â‹£
`NotSubset;`	U+02282 U+020D2	âŠ‚âƒ’
`NotSubsetEqual;`	U+02288	âŠˆ
`NotSucceeds;`	U+02281	âŠ
`NotSucceedsEqual;`	U+02AB0 U+00338	âª°Ì¸
`NotSucceedsSlantEqual;`	U+022E1	â‹¡
`NotSucceedsTilde;`	U+0227F U+00338	â‰¿Ì¸
`NotSuperset;`	U+02283 U+020D2	âŠƒâƒ’
`NotSupersetEqual;`	U+02289	âŠ‰
`NotTilde;`	U+02241	â‰
`NotTildeEqual;`	U+02244	â‰„
`NotTildeFullEqual;`	U+02247	â‰‡
`NotTildeTilde;`	U+02249	â‰‰
`NotVerticalBar;`	U+02224	âˆ¤
`npar;`	U+02226	âˆ¦
`nparallel;`	U+02226	âˆ¦
`nparsl;`	U+02AFD U+020E5	â«½âƒ¥
`npart;`	U+02202 U+00338	âˆ‚Ì¸
`npolint;`	U+02A14	â¨”
`npr;`	U+02280	âŠ€
`nprcue;`	U+022E0	â‹
`npre;`	U+02AAF U+00338	âª¯Ì¸
`nprec;`	U+02280	âŠ€
`npreceq;`	U+02AAF U+00338	âª¯Ì¸
`nrArr;`	U+021CF	â‡
`nrarr;`	U+0219B	â†›
`nrarrc;`	U+02933 U+00338	â¤³Ì¸
`nrarrw;`	U+0219D U+00338	â†Ì¸
`nRightarrow;`	U+021CF	â‡
`nrightarrow;`	U+0219B	â†›
`nrtri;`	U+022EB	â‹«
`nrtrie;`	U+022ED	â‹
`nsc;`	U+02281	âŠ
`nsccue;`	U+022E1	â‹¡
`nsce;`	U+02AB0 U+00338	âª°Ì¸
`Nscr;`	U+1D4A9	ð’©
`nscr;`	U+1D4C3	ð“ƒ
`nshortmid;`	U+02224	âˆ¤
`nshortparallel;`	U+02226	âˆ¦
`nsim;`	U+02241	â‰
`nsime;`	U+02244	â‰„
`nsimeq;`	U+02244	â‰„
`nsmid;`	U+02224	âˆ¤
`nspar;`	U+02226	âˆ¦
`nsqsube;`	U+022E2	â‹¢
`nsqsupe;`	U+022E3	â‹£
`nsub;`	U+02284	âŠ„
`nsubE;`	U+02AC5 U+00338	â«…Ì¸
`nsube;`	U+02288	âŠˆ
`nsubset;`	U+02282 U+020D2	âŠ‚âƒ’
`nsubseteq;`	U+02288	âŠˆ
`nsubseteqq;`	U+02AC5 U+00338	â«…Ì¸
`nsucc;`	U+02281	âŠ
`nsucceq;`	U+02AB0 U+00338	âª°Ì¸
`nsup;`	U+02285	âŠ…
`nsupE;`	U+02AC6 U+00338	â«†Ì¸
`nsupe;`	U+02289	âŠ‰
`nsupset;`	U+02283 U+020D2	âŠƒâƒ’
`nsupseteq;`	U+02289	âŠ‰
`nsupseteqq;`	U+02AC6 U+00338	â«†Ì¸
`ntgl;`	U+02279	â‰¹
`Ntilde;`	U+000D1	Ã‘
`ntilde;`	U+000F1	Ã±
`ntlg;`	U+02278	â‰¸
`ntriangleleft;`	U+022EA	â‹ª
`ntrianglelefteq;`	U+022EC	â‹¬
`ntriangleright;`	U+022EB	â‹«
`ntrianglerighteq;`	U+022ED	â‹
`Nu;`	U+0039D	Î
`nu;`	U+003BD	Î½
`num;`	U+00023	#
`numero;`	U+02116	â„–
`numsp;`	U+02007	â€‡
`nvap;`	U+0224D U+020D2	â‰âƒ’
`nVDash;`	U+022AF	âŠ¯
`nVdash;`	U+022AE	âŠ®
`nvDash;`	U+022AD	âŠ
`nvdash;`	U+022AC	âŠ¬
`nvge;`	U+02265 U+020D2	â‰¥âƒ’
`nvgt;`	U+0003E U+020D2	>âƒ’
`nvHarr;`	U+02904	â¤„
`nvinfin;`	U+029DE	â§ž
`nvlArr;`	U+02902	â¤‚
`nvle;`	U+02264 U+020D2	â‰¤âƒ’
`nvlt;`	U+0003C U+020D2	<âƒ’
`nvltrie;`	U+022B4 U+020D2	âŠ´âƒ’
`nvrArr;`	U+02903	â¤ƒ
`nvrtrie;`	U+022B5 U+020D2	âŠµâƒ’
`nvsim;`	U+0223C U+020D2	âˆ¼âƒ’
`nwarhk;`	U+02923	â¤£
`nwArr;`	U+021D6	â‡–
`nwarr;`	U+02196	â†–
`nwarrow;`	U+02196	â†–
`nwnear;`	U+02927	â¤§
`Oacute;`	U+000D3	Ã“
`oacute;`	U+000F3	Ã³
`oast;`	U+0229B	âŠ›
`ocir;`	U+0229A	âŠš
`Ocirc;`	U+000D4	Ã”
`ocirc;`	U+000F4	Ã´
`Ocy;`	U+0041E	Ðž
`ocy;`	U+0043E	Ð¾
`odash;`	U+0229D	âŠ
`Odblac;`	U+00150	Å
`odblac;`	U+00151	Å‘
`odiv;`	U+02A38	â¨¸
`odot;`	U+02299	âŠ™
`odsold;`	U+029BC	â¦¼
`OElig;`	U+00152	Å’
`oelig;`	U+00153	Å“
`ofcir;`	U+029BF	â¦¿
`Ofr;`	U+1D512	ð”’
`ofr;`	U+1D52C	ð”¬
`ogon;`	U+002DB	Ë›
`Ograve;`	U+000D2	Ã’
`ograve;`	U+000F2	Ã²
`ogt;`	U+029C1	â§
`ohbar;`	U+029B5	â¦µ
`ohm;`	U+003A9	Î©
`oint;`	U+0222E	âˆ®
`olarr;`	U+021BA	â†º
`olcir;`	U+029BE	â¦¾
`olcross;`	U+029BB	â¦»
`oline;`	U+0203E	â€¾
`olt;`	U+029C0	â§€
`Omacr;`	U+0014C	ÅŒ
`omacr;`	U+0014D	Å
`Omega;`	U+003A9	Î©
`omega;`	U+003C9	Ï‰
`Omicron;`	U+0039F	ÎŸ
`omicron;`	U+003BF	Î¿
`omid;`	U+029B6	â¦¶
`ominus;`	U+02296	âŠ–
`Oopf;`	U+1D546	ð•†
`oopf;`	U+1D560	ð•
`opar;`	U+029B7	â¦·
`OpenCurlyDoubleQuote;`	U+0201C	â€œ
`OpenCurlyQuote;`	U+02018	â€˜
`operp;`	U+029B9	â¦¹
`oplus;`	U+02295	âŠ•
`Or;`	U+02A54	â©”
`or;`	U+02228	âˆ¨
`orarr;`	U+021BB	â†»
`ord;`	U+02A5D	â©
`order;`	U+02134	â„´
`orderof;`	U+02134	â„´
`ordf;`	U+000AA	Âª
`ordm;`	U+000BA	Âº
`origof;`	U+022B6	âŠ¶
`oror;`	U+02A56	â©–
`orslope;`	U+02A57	â©—
`orv;`	U+02A5B	â©›
`oS;`	U+024C8	â“ˆ
`Oscr;`	U+1D4AA	ð’ª
`oscr;`	U+02134	â„´
`Oslash;`	U+000D8	Ã˜
`oslash;`	U+000F8	Ã¸
`osol;`	U+02298	âŠ˜
`Otilde;`	U+000D5	Ã•
`otilde;`	U+000F5	Ãµ
`Otimes;`	U+02A37	â¨·
`otimes;`	U+02297	âŠ—
`otimesas;`	U+02A36	â¨¶
`Ouml;`	U+000D6	Ã–
`ouml;`	U+000F6	Ã¶
`ovbar;`	U+0233D	âŒ½
`OverBar;`	U+0203E	â€¾
`OverBrace;`	U+023DE	âž
`OverBracket;`	U+023B4	âŽ´
`OverParenthesis;`	U+023DC	âœ
`par;`	U+02225	âˆ¥
`para;`	U+000B6	Â¶
`parallel;`	U+02225	âˆ¥
`parsim;`	U+02AF3	â«³
`parsl;`	U+02AFD	â«½
`part;`	U+02202	âˆ‚
`PartialD;`	U+02202	âˆ‚
`Pcy;`	U+0041F	ÐŸ
`pcy;`	U+0043F	Ð¿
`percnt;`	U+00025	%
`period;`	U+0002E	.
`permil;`	U+02030	â€°
`perp;`	U+022A5	âŠ¥
`pertenk;`	U+02031	â€±
`Pfr;`	U+1D513	ð”“
`pfr;`	U+1D52D	ð”
`Phi;`	U+003A6	Î¦
`phi;`	U+003C6	Ï†
`phiv;`	U+003D5	Ï•
`phmmat;`	U+02133	â„³
`phone;`	U+0260E	â˜Ž
`Pi;`	U+003A0	Î
`pi;`	U+003C0	Ï€
`pitchfork;`	U+022D4	â‹”
`piv;`	U+003D6	Ï–
`planck;`	U+0210F	â„
`planckh;`	U+0210E	â„Ž
`plankv;`	U+0210F	â„
`plus;`	U+0002B	+
`plusacir;`	U+02A23	â¨£
`plusb;`	U+0229E	âŠž
`pluscir;`	U+02A22	â¨¢
`plusdo;`	U+02214	âˆ”
`plusdu;`	U+02A25	â¨¥
`pluse;`	U+02A72	â©²
`PlusMinus;`	U+000B1	Â±
`plusmn;`	U+000B1	Â±
`plussim;`	U+02A26	â¨¦
`plustwo;`	U+02A27	â¨§
`pm;`	U+000B1	Â±
`Poincareplane;`	U+0210C	â„Œ
`pointint;`	U+02A15	â¨•
`Popf;`	U+02119	â„™
`popf;`	U+1D561	ð•¡
`pound;`	U+000A3	Â£
`Pr;`	U+02ABB	âª»
`pr;`	U+0227A	â‰º
`prap;`	U+02AB7	âª·
`prcue;`	U+0227C	â‰¼
`prE;`	U+02AB3	âª³
`pre;`	U+02AAF	âª¯
`prec;`	U+0227A	â‰º
`precapprox;`	U+02AB7	âª·
`preccurlyeq;`	U+0227C	â‰¼
`Precedes;`	U+0227A	â‰º
`PrecedesEqual;`	U+02AAF	âª¯
`PrecedesSlantEqual;`	U+0227C	â‰¼
`PrecedesTilde;`	U+0227E	â‰¾
`preceq;`	U+02AAF	âª¯
`precnapprox;`	U+02AB9	âª¹
`precneqq;`	U+02AB5	âªµ
`precnsim;`	U+022E8	â‹¨
`precsim;`	U+0227E	â‰¾
`Prime;`	U+02033	â€³
`prime;`	U+02032	â€²
`primes;`	U+02119	â„™
`prnap;`	U+02AB9	âª¹
`prnE;`	U+02AB5	âªµ
`prnsim;`	U+022E8	â‹¨
`prod;`	U+0220F	âˆ
`Product;`	U+0220F	âˆ
`profalar;`	U+0232E	âŒ®
`profline;`	U+02312	âŒ’
`profsurf;`	U+02313	âŒ“
`prop;`	U+0221D	âˆ
`Proportion;`	U+02237	âˆ·
`Proportional;`	U+0221D	âˆ
`propto;`	U+0221D	âˆ
`prsim;`	U+0227E	â‰¾
`prurel;`	U+022B0	âŠ°
`Pscr;`	U+1D4AB	ð’«
`pscr;`	U+1D4C5	ð“…
`Psi;`	U+003A8	Î¨
`psi;`	U+003C8	Ïˆ
`puncsp;`	U+02008	â€ˆ
`Qfr;`	U+1D514	ð””
`qfr;`	U+1D52E	ð”®
`qint;`	U+02A0C	â¨Œ
`Qopf;`	U+0211A	â„š
`qopf;`	U+1D562	ð•¢
`qprime;`	U+02057	â—
`Qscr;`	U+1D4AC	ð’¬
`qscr;`	U+1D4C6	ð“†
`quaternions;`	U+0210D	â„
`quatint;`	U+02A16	â¨–
`quest;`	U+0003F	?
`questeq;`	U+0225F	â‰Ÿ
`QUOT;`	U+00022	"
`quot;`	U+00022	"
`rAarr;`	U+021DB	â‡›
`race;`	U+0223D U+00331	âˆ½Ì±
`Racute;`	U+00154	Å”
`racute;`	U+00155	Å•
`radic;`	U+0221A	âˆš
`raemptyv;`	U+029B3	â¦³
`Rang;`	U+027EB	âŸ«
`rang;`	U+027E9	âŸ©
`rangd;`	U+02992	â¦’
`range;`	U+029A5	â¦¥
`rangle;`	U+027E9	âŸ©
`raquo;`	U+000BB	Â»
`Rarr;`	U+021A0	â†
`rArr;`	U+021D2	â‡’
`rarr;`	U+02192	â†’
`rarrap;`	U+02975	â¥µ
`rarrb;`	U+021E5	â‡¥
`rarrbfs;`	U+02920	â¤
`rarrc;`	U+02933	â¤³
`rarrfs;`	U+0291E	â¤ž
`rarrhk;`	U+021AA	â†ª
`rarrlp;`	U+021AC	â†¬
`rarrpl;`	U+02945	â¥…
`rarrsim;`	U+02974	â¥´
`Rarrtl;`	U+02916	â¤–
`rarrtl;`	U+021A3	â†£
`rarrw;`	U+0219D	â†
`rAtail;`	U+0291C	â¤œ
`ratail;`	U+0291A	â¤š
`ratio;`	U+02236	âˆ¶
`rationals;`	U+0211A	â„š
`RBarr;`	U+02910	â¤
`rBarr;`	U+0290F	â¤
`rbarr;`	U+0290D	â¤
`rbbrk;`	U+02773	â³
`rbrace;`	U+0007D	}
`rbrack;`	U+0005D	]
`rbrke;`	U+0298C	â¦Œ
`rbrksld;`	U+0298E	â¦Ž
`rbrkslu;`	U+02990	â¦
`Rcaron;`	U+00158	Å˜
`rcaron;`	U+00159	Å™
`Rcedil;`	U+00156	Å–
`rcedil;`	U+00157	Å—
`rceil;`	U+02309	âŒ‰
`rcub;`	U+0007D	}
`Rcy;`	U+00420	Ð
`rcy;`	U+00440	Ñ€
`rdca;`	U+02937	â¤·
`rdldhar;`	U+02969	â¥©
`rdquo;`	U+0201D	â€
`rdquor;`	U+0201D	â€
`rdsh;`	U+021B3	â†³
`Re;`	U+0211C	â„œ
`real;`	U+0211C	â„œ
`realine;`	U+0211B	â„›
`realpart;`	U+0211C	â„œ
`reals;`	U+0211D	â„
`rect;`	U+025AD	â–
`REG;`	U+000AE	Â®
`reg;`	U+000AE	Â®
`ReverseElement;`	U+0220B	âˆ‹
`ReverseEquilibrium;`	U+021CB	â‡‹
`ReverseUpEquilibrium;`	U+0296F	â¥¯
`rfisht;`	U+0297D	â¥½
`rfloor;`	U+0230B	âŒ‹
`Rfr;`	U+0211C	â„œ
`rfr;`	U+1D52F	ð”¯
`rHar;`	U+02964	â¥¤
`rhard;`	U+021C1	â‡
`rharu;`	U+021C0	â‡€
`rharul;`	U+0296C	â¥¬
`Rho;`	U+003A1	Î¡
`rho;`	U+003C1	Ï
`rhov;`	U+003F1	Ï±
`RightAngleBracket;`	U+027E9	âŸ©
`RightArrow;`	U+02192	â†’
`Rightarrow;`	U+021D2	â‡’
`rightarrow;`	U+02192	â†’
`RightArrowBar;`	U+021E5	â‡¥
`RightArrowLeftArrow;`	U+021C4	â‡„
`rightarrowtail;`	U+021A3	â†£
`RightCeiling;`	U+02309	âŒ‰
`RightDoubleBracket;`	U+027E7	âŸ§
`RightDownTeeVector;`	U+0295D	â¥
`RightDownVector;`	U+021C2	â‡‚
`RightDownVectorBar;`	U+02955	â¥•
`RightFloor;`	U+0230B	âŒ‹
`rightharpoondown;`	U+021C1	â‡
`rightharpoonup;`	U+021C0	â‡€
`rightleftarrows;`	U+021C4	â‡„
`rightleftharpoons;`	U+021CC	â‡Œ
`rightrightarrows;`	U+021C9	â‡‰
`rightsquigarrow;`	U+0219D	â†
`RightTee;`	U+022A2	âŠ¢
`RightTeeArrow;`	U+021A6	â†¦
`RightTeeVector;`	U+0295B	â¥›
`rightthreetimes;`	U+022CC	â‹Œ
`RightTriangle;`	U+022B3	âŠ³
`RightTriangleBar;`	U+029D0	â§
`RightTriangleEqual;`	U+022B5	âŠµ
`RightUpDownVector;`	U+0294F	â¥
`RightUpTeeVector;`	U+0295C	â¥œ
`RightUpVector;`	U+021BE	â†¾
`RightUpVectorBar;`	U+02954	â¥”
`RightVector;`	U+021C0	â‡€
`RightVectorBar;`	U+02953	â¥“
`ring;`	U+002DA	Ëš
`risingdotseq;`	U+02253	â‰“
`rlarr;`	U+021C4	â‡„
`rlhar;`	U+021CC	â‡Œ
`rlm;`	U+0200F	â€
`rmoust;`	U+023B1	âŽ±
`rmoustache;`	U+023B1	âŽ±
`rnmid;`	U+02AEE	â«®
`roang;`	U+027ED	âŸ
`roarr;`	U+021FE	â‡¾
`robrk;`	U+027E7	âŸ§
`ropar;`	U+02986	â¦†
`Ropf;`	U+0211D	â„
`ropf;`	U+1D563	ð•£
`roplus;`	U+02A2E	â¨®
`rotimes;`	U+02A35	â¨µ
`RoundImplies;`	U+02970	â¥°
`rpar;`	U+00029	)
`rpargt;`	U+02994	â¦”
`rppolint;`	U+02A12	â¨’
`rrarr;`	U+021C9	â‡‰
`Rrightarrow;`	U+021DB	â‡›
`rsaquo;`	U+0203A	â€º
`Rscr;`	U+0211B	â„›
`rscr;`	U+1D4C7	ð“‡
`Rsh;`	U+021B1	â†±
`rsh;`	U+021B1	â†±
`rsqb;`	U+0005D	]
`rsquo;`	U+02019	â€™
`rsquor;`	U+02019	â€™
`rthree;`	U+022CC	â‹Œ
`rtimes;`	U+022CA	â‹Š
`rtri;`	U+025B9	â–¹
`rtrie;`	U+022B5	âŠµ
`rtrif;`	U+025B8	â–¸
`rtriltri;`	U+029CE	â§Ž
`RuleDelayed;`	U+029F4	â§´
`ruluhar;`	U+02968	â¥¨
`rx;`	U+0211E	â„ž
`Sacute;`	U+0015A	Åš
`sacute;`	U+0015B	Å›
`sbquo;`	U+0201A	â€š
`Sc;`	U+02ABC	âª¼
`sc;`	U+0227B	â‰»
`scap;`	U+02AB8	âª¸
`Scaron;`	U+00160	Å
`scaron;`	U+00161	Å¡
`sccue;`	U+0227D	â‰½
`scE;`	U+02AB4	âª´
`sce;`	U+02AB0	âª°
`Scedil;`	U+0015E	Åž
`scedil;`	U+0015F	ÅŸ
`Scirc;`	U+0015C	Åœ
`scirc;`	U+0015D	Å
`scnap;`	U+02ABA	âªº
`scnE;`	U+02AB6	âª¶
`scnsim;`	U+022E9	â‹©
`scpolint;`	U+02A13	â¨“
`scsim;`	U+0227F	â‰¿
`Scy;`	U+00421	Ð¡
`scy;`	U+00441	Ñ
`sdot;`	U+022C5	â‹…
`sdotb;`	U+022A1	âŠ¡
`sdote;`	U+02A66	â©¦
`searhk;`	U+02925	â¤¥
`seArr;`	U+021D8	â‡˜
`searr;`	U+02198	â†˜
`searrow;`	U+02198	â†˜
`sect;`	U+000A7	Â§
`semi;`	U+0003B	;
`seswar;`	U+02929	â¤©
`setminus;`	U+02216	âˆ–
`setmn;`	U+02216	âˆ–
`sext;`	U+02736	âœ¶
`Sfr;`	U+1D516	ð”–
`sfr;`	U+1D530	ð”°
`sfrown;`	U+02322	âŒ¢
`sharp;`	U+0266F	â™¯
`SHCHcy;`	U+00429	Ð©
`shchcy;`	U+00449	Ñ‰
`SHcy;`	U+00428	Ð¨
`shcy;`	U+00448	Ñˆ
`ShortDownArrow;`	U+02193	â†“
`ShortLeftArrow;`	U+02190	â†
`shortmid;`	U+02223	âˆ£
`shortparallel;`	U+02225	âˆ¥
`ShortRightArrow;`	U+02192	â†’
`ShortUpArrow;`	U+02191	â†‘
`shy;`	U+000AD	Â
`Sigma;`	U+003A3	Î£
`sigma;`	U+003C3	Ïƒ
`sigmaf;`	U+003C2	Ï‚
`sigmav;`	U+003C2	Ï‚
`sim;`	U+0223C	âˆ¼
`simdot;`	U+02A6A	â©ª
`sime;`	U+02243	â‰ƒ
`simeq;`	U+02243	â‰ƒ
`simg;`	U+02A9E	âªž
`simgE;`	U+02AA0	âª
`siml;`	U+02A9D	âª
`simlE;`	U+02A9F	âªŸ
`simne;`	U+02246	â‰†
`simplus;`	U+02A24	â¨¤
`simrarr;`	U+02972	â¥²
`slarr;`	U+02190	â†
`SmallCircle;`	U+02218	âˆ˜
`smallsetminus;`	U+02216	âˆ–
`smashp;`	U+02A33	â¨³
`smeparsl;`	U+029E4	â§¤
`smid;`	U+02223	âˆ£
`smile;`	U+02323	âŒ£
`smt;`	U+02AAA	âªª
`smte;`	U+02AAC	âª¬
`smtes;`	U+02AAC U+0FE00	âª¬ï¸€
`SOFTcy;`	U+0042C	Ð¬
`softcy;`	U+0044C	ÑŒ
`sol;`	U+0002F	/
`solb;`	U+029C4	â§„
`solbar;`	U+0233F	âŒ¿
`Sopf;`	U+1D54A	ð•Š
`sopf;`	U+1D564	ð•¤
`spades;`	U+02660	â™
`spadesuit;`	U+02660	â™
`spar;`	U+02225	âˆ¥
`sqcap;`	U+02293	âŠ“
`sqcaps;`	U+02293 U+0FE00	âŠ“ï¸€
`sqcup;`	U+02294	âŠ”
`sqcups;`	U+02294 U+0FE00	âŠ”ï¸€
`Sqrt;`	U+0221A	âˆš
`sqsub;`	U+0228F	âŠ
`sqsube;`	U+02291	âŠ‘
`sqsubset;`	U+0228F	âŠ
`sqsubseteq;`	U+02291	âŠ‘
`sqsup;`	U+02290	âŠ
`sqsupe;`	U+02292	âŠ’
`sqsupset;`	U+02290	âŠ
`sqsupseteq;`	U+02292	âŠ’
`squ;`	U+025A1	â–¡
`Square;`	U+025A1	â–¡
`square;`	U+025A1	â–¡
`SquareIntersection;`	U+02293	âŠ“
`SquareSubset;`	U+0228F	âŠ
`SquareSubsetEqual;`	U+02291	âŠ‘
`SquareSuperset;`	U+02290	âŠ
`SquareSupersetEqual;`	U+02292	âŠ’
`SquareUnion;`	U+02294	âŠ”
`squarf;`	U+025AA	â–ª
`squf;`	U+025AA	â–ª
`srarr;`	U+02192	â†’
`Sscr;`	U+1D4AE	ð’®
`sscr;`	U+1D4C8	ð“ˆ
`ssetmn;`	U+02216	âˆ–
`ssmile;`	U+02323	âŒ£
`sstarf;`	U+022C6	â‹†
`Star;`	U+022C6	â‹†
`star;`	U+02606	â˜†
`starf;`	U+02605	â˜…
`straightepsilon;`	U+003F5	Ïµ
`straightphi;`	U+003D5	Ï•
`strns;`	U+000AF	Â¯
`Sub;`	U+022D0	â‹
`sub;`	U+02282	âŠ‚
`subdot;`	U+02ABD	âª½
`subE;`	U+02AC5	â«…
`sube;`	U+02286	âŠ†
`subedot;`	U+02AC3	â«ƒ
`submult;`	U+02AC1	â«
`subnE;`	U+02ACB	â«‹
`subne;`	U+0228A	âŠŠ
`subplus;`	U+02ABF	âª¿
`subrarr;`	U+02979	â¥¹
`Subset;`	U+022D0	â‹
`subset;`	U+02282	âŠ‚
`subseteq;`	U+02286	âŠ†
`subseteqq;`	U+02AC5	â«…
`SubsetEqual;`	U+02286	âŠ†
`subsetneq;`	U+0228A	âŠŠ
`subsetneqq;`	U+02ACB	â«‹
`subsim;`	U+02AC7	â«‡
`subsub;`	U+02AD5	â«•
`subsup;`	U+02AD3	â«“
`succ;`	U+0227B	â‰»
`succapprox;`	U+02AB8	âª¸
`succcurlyeq;`	U+0227D	â‰½
`Succeeds;`	U+0227B	â‰»
`SucceedsEqual;`	U+02AB0	âª°
`SucceedsSlantEqual;`	U+0227D	â‰½
`SucceedsTilde;`	U+0227F	â‰¿
`succeq;`	U+02AB0	âª°
`succnapprox;`	U+02ABA	âªº
`succneqq;`	U+02AB6	âª¶
`succnsim;`	U+022E9	â‹©
`succsim;`	U+0227F	â‰¿
`SuchThat;`	U+0220B	âˆ‹
`Sum;`	U+02211	âˆ‘
`sum;`	U+02211	âˆ‘
`sung;`	U+0266A	â™ª
`Sup;`	U+022D1	â‹‘
`sup;`	U+02283	âŠƒ
`sup1;`	U+000B9	Â¹
`sup2;`	U+000B2	Â²
`sup3;`	U+000B3	Â³
`supdot;`	U+02ABE	âª¾
`supdsub;`	U+02AD8	â«˜
`supE;`	U+02AC6	â«†
`supe;`	U+02287	âŠ‡
`supedot;`	U+02AC4	â«„
`Superset;`	U+02283	âŠƒ
`SupersetEqual;`	U+02287	âŠ‡
`suphsol;`	U+027C9	âŸ‰
`suphsub;`	U+02AD7	â«—
`suplarr;`	U+0297B	â¥»
`supmult;`	U+02AC2	â«‚
`supnE;`	U+02ACC	â«Œ
`supne;`	U+0228B	âŠ‹
`supplus;`	U+02AC0	â«€
`Supset;`	U+022D1	â‹‘
`supset;`	U+02283	âŠƒ
`supseteq;`	U+02287	âŠ‡
`supseteqq;`	U+02AC6	â«†
`supsetneq;`	U+0228B	âŠ‹
`supsetneqq;`	U+02ACC	â«Œ
`supsim;`	U+02AC8	â«ˆ
`supsub;`	U+02AD4	â«”
`supsup;`	U+02AD6	â«–
`swarhk;`	U+02926	â¤¦
`swArr;`	U+021D9	â‡™
`swarr;`	U+02199	â†™
`swarrow;`	U+02199	â†™
`swnwar;`	U+0292A	â¤ª
`szlig;`	U+000DF	ÃŸ
`Tab;`	U+00009	â‰
`target;`	U+02316	âŒ–
`Tau;`	U+003A4	Î¤
`tau;`	U+003C4	Ï„
`tbrk;`	U+023B4	âŽ´
`Tcaron;`	U+00164	Å¤
`tcaron;`	U+00165	Å¥
`Tcedil;`	U+00162	Å¢
`tcedil;`	U+00163	Å£
`Tcy;`	U+00422	Ð¢
`tcy;`	U+00442	Ñ‚
`tdot;`	U+020DB	â—Œâƒ›
`telrec;`	U+02315	âŒ•
`Tfr;`	U+1D517	ð”—
`tfr;`	U+1D531	ð”±
`there4;`	U+02234	âˆ´
`Therefore;`	U+02234	âˆ´
`therefore;`	U+02234	âˆ´
`Theta;`	U+00398	Î˜
`theta;`	U+003B8	Î¸
`thetasym;`	U+003D1	Ï‘
`thetav;`	U+003D1	Ï‘
`thickapprox;`	U+02248	â‰ˆ
`thicksim;`	U+0223C	âˆ¼
`ThickSpace;`	U+0205F U+0200A	âŸâ€Š
`thinsp;`	U+02009	â€‰
`ThinSpace;`	U+02009	â€‰
`thkap;`	U+02248	â‰ˆ
`thksim;`	U+0223C	âˆ¼
`THORN;`	U+000DE	Ãž
`thorn;`	U+000FE	Ã¾
`Tilde;`	U+0223C	âˆ¼
`tilde;`	U+002DC	Ëœ
`TildeEqual;`	U+02243	â‰ƒ
`TildeFullEqual;`	U+02245	â‰…
`TildeTilde;`	U+02248	â‰ˆ
`times;`	U+000D7	Ã—
`timesb;`	U+022A0	âŠ
`timesbar;`	U+02A31	â¨±
`timesd;`	U+02A30	â¨°
`tint;`	U+0222D	âˆ
`toea;`	U+02928	â¤¨
`top;`	U+022A4	âŠ¤
`topbot;`	U+02336	âŒ¶
`topcir;`	U+02AF1	â«±
`Topf;`	U+1D54B	ð•‹
`topf;`	U+1D565	ð•¥
`topfork;`	U+02ADA	â«š
`tosa;`	U+02929	â¤©
`tprime;`	U+02034	â€´
`TRADE;`	U+02122	â„¢
`trade;`	U+02122	â„¢
`triangle;`	U+025B5	â–µ
`triangledown;`	U+025BF	â–¿
`triangleleft;`	U+025C3	â—ƒ
`trianglelefteq;`	U+022B4	âŠ´
`triangleq;`	U+0225C	â‰œ
`triangleright;`	U+025B9	â–¹
`trianglerighteq;`	U+022B5	âŠµ
`tridot;`	U+025EC	â—¬
`trie;`	U+0225C	â‰œ
`triminus;`	U+02A3A	â¨º
`TripleDot;`	U+020DB	â—Œâƒ›
`triplus;`	U+02A39	â¨¹
`trisb;`	U+029CD	â§
`tritime;`	U+02A3B	â¨»
`trpezium;`	U+023E2	â¢
`Tscr;`	U+1D4AF	ð’¯
`tscr;`	U+1D4C9	ð“‰
`TScy;`	U+00426	Ð¦
`tscy;`	U+00446	Ñ†
`TSHcy;`	U+0040B	Ð‹
`tshcy;`	U+0045B	Ñ›
`Tstrok;`	U+00166	Å¦
`tstrok;`	U+00167	Å§
`twixt;`	U+0226C	â‰¬
`twoheadleftarrow;`	U+0219E	â†ž
`twoheadrightarrow;`	U+021A0	â†
`Uacute;`	U+000DA	Ãš
`uacute;`	U+000FA	Ãº
`Uarr;`	U+0219F	â†Ÿ
`uArr;`	U+021D1	â‡‘
`uarr;`	U+02191	â†‘
`Uarrocir;`	U+02949	â¥‰
`Ubrcy;`	U+0040E	ÐŽ
`ubrcy;`	U+0045E	Ñž
`Ubreve;`	U+0016C	Å¬
`ubreve;`	U+0016D	Å
`Ucirc;`	U+000DB	Ã›
`ucirc;`	U+000FB	Ã»
`Ucy;`	U+00423	Ð£
`ucy;`	U+00443	Ñƒ
`udarr;`	U+021C5	â‡…
`Udblac;`	U+00170	Å°
`udblac;`	U+00171	Å±
`udhar;`	U+0296E	â¥®
`ufisht;`	U+0297E	â¥¾
`Ufr;`	U+1D518	ð”˜
`ufr;`	U+1D532	ð”²
`Ugrave;`	U+000D9	Ã™
`ugrave;`	U+000F9	Ã¹
`uHar;`	U+02963	â¥£
`uharl;`	U+021BF	â†¿
`uharr;`	U+021BE	â†¾
`uhblk;`	U+02580	â–€
`ulcorn;`	U+0231C	âŒœ
`ulcorner;`	U+0231C	âŒœ
`ulcrop;`	U+0230F	âŒ
`ultri;`	U+025F8	â—¸
`Umacr;`	U+0016A	Åª
`umacr;`	U+0016B	Å«
`uml;`	U+000A8	Â¨
`UnderBar;`	U+0005F	_
`UnderBrace;`	U+023DF	âŸ
`UnderBracket;`	U+023B5	âŽµ
`UnderParenthesis;`	U+023DD	â
`Union;`	U+022C3	â‹ƒ
`UnionPlus;`	U+0228E	âŠŽ
`Uogon;`	U+00172	Å²
`uogon;`	U+00173	Å³
`Uopf;`	U+1D54C	ð•Œ
`uopf;`	U+1D566	ð•¦
`UpArrow;`	U+02191	â†‘
`Uparrow;`	U+021D1	â‡‘
`uparrow;`	U+02191	â†‘
`UpArrowBar;`	U+02912	â¤’
`UpArrowDownArrow;`	U+021C5	â‡…
`UpDownArrow;`	U+02195	â†•
`Updownarrow;`	U+021D5	â‡•
`updownarrow;`	U+02195	â†•
`UpEquilibrium;`	U+0296E	â¥®
`upharpoonleft;`	U+021BF	â†¿
`upharpoonright;`	U+021BE	â†¾
`uplus;`	U+0228E	âŠŽ
`UpperLeftArrow;`	U+02196	â†–
`UpperRightArrow;`	U+02197	â†—
`Upsi;`	U+003D2	Ï’
`upsi;`	U+003C5	Ï…
`upsih;`	U+003D2	Ï’
`Upsilon;`	U+003A5	Î¥
`upsilon;`	U+003C5	Ï…
`UpTee;`	U+022A5	âŠ¥
`UpTeeArrow;`	U+021A5	â†¥
`upuparrows;`	U+021C8	â‡ˆ
`urcorn;`	U+0231D	âŒ
`urcorner;`	U+0231D	âŒ
`urcrop;`	U+0230E	âŒŽ
`Uring;`	U+0016E	Å®
`uring;`	U+0016F	Å¯
`urtri;`	U+025F9	â—¹
`Uscr;`	U+1D4B0	ð’°
`uscr;`	U+1D4CA	ð“Š
`utdot;`	U+022F0	â‹°
`Utilde;`	U+00168	Å¨
`utilde;`	U+00169	Å©
`utri;`	U+025B5	â–µ
`utrif;`	U+025B4	â–´
`uuarr;`	U+021C8	â‡ˆ
`Uuml;`	U+000DC	Ãœ
`uuml;`	U+000FC	Ã¼
`uwangle;`	U+029A7	â¦§
`vangrt;`	U+0299C	â¦œ
`varepsilon;`	U+003F5	Ïµ
`varkappa;`	U+003F0	Ï°
`varnothing;`	U+02205	âˆ…
`varphi;`	U+003D5	Ï•
`varpi;`	U+003D6	Ï–
`varpropto;`	U+0221D	âˆ
`vArr;`	U+021D5	â‡•
`varr;`	U+02195	â†•
`varrho;`	U+003F1	Ï±
`varsigma;`	U+003C2	Ï‚
`varsubsetneq;`	U+0228A U+0FE00	âŠŠï¸€
`varsubsetneqq;`	U+02ACB U+0FE00	â«‹ï¸€
`varsupsetneq;`	U+0228B U+0FE00	âŠ‹ï¸€
`varsupsetneqq;`	U+02ACC U+0FE00	â«Œï¸€
`vartheta;`	U+003D1	Ï‘
`vartriangleleft;`	U+022B2	âŠ²
`vartriangleright;`	U+022B3	âŠ³
`Vbar;`	U+02AEB	â««
`vBar;`	U+02AE8	â«¨
`vBarv;`	U+02AE9	â«©
`Vcy;`	U+00412	Ð’
`vcy;`	U+00432	Ð²
`VDash;`	U+022AB	âŠ«
`Vdash;`	U+022A9	âŠ©
`vDash;`	U+022A8	âŠ¨
`vdash;`	U+022A2	âŠ¢
`Vdashl;`	U+02AE6	â«¦
`Vee;`	U+022C1	â‹
`vee;`	U+02228	âˆ¨
`veebar;`	U+022BB	âŠ»
`veeeq;`	U+0225A	â‰š
`vellip;`	U+022EE	â‹®
`Verbar;`	U+02016	â€–
`verbar;`	U+0007C	\|
`Vert;`	U+02016	â€–
`vert;`	U+0007C	\|
`VerticalBar;`	U+02223	âˆ£
`VerticalLine;`	U+0007C	\|
`VerticalSeparator;`	U+02758	â˜
`VerticalTilde;`	U+02240	â‰€
`VeryThinSpace;`	U+0200A	â€Š
`Vfr;`	U+1D519	ð”™
`vfr;`	U+1D533	ð”³
`vltri;`	U+022B2	âŠ²
`vnsub;`	U+02282 U+020D2	âŠ‚âƒ’
`vnsup;`	U+02283 U+020D2	âŠƒâƒ’
`Vopf;`	U+1D54D	ð•
`vopf;`	U+1D567	ð•§
`vprop;`	U+0221D	âˆ
`vrtri;`	U+022B3	âŠ³
`Vscr;`	U+1D4B1	ð’±
`vscr;`	U+1D4CB	ð“‹
`vsubnE;`	U+02ACB U+0FE00	â«‹ï¸€
`vsubne;`	U+0228A U+0FE00	âŠŠï¸€
`vsupnE;`	U+02ACC U+0FE00	â«Œï¸€
`vsupne;`	U+0228B U+0FE00	âŠ‹ï¸€
`Vvdash;`	U+022AA	âŠª
`vzigzag;`	U+0299A	â¦š
`Wcirc;`	U+00174	Å´
`wcirc;`	U+00175	Åµ
`wedbar;`	U+02A5F	â©Ÿ
`Wedge;`	U+022C0	â‹€
`wedge;`	U+02227	âˆ§
`wedgeq;`	U+02259	â‰™
`weierp;`	U+02118	â„˜
`Wfr;`	U+1D51A	ð”š
`wfr;`	U+1D534	ð”´
`Wopf;`	U+1D54E	ð•Ž
`wopf;`	U+1D568	ð•¨
`wp;`	U+02118	â„˜
`wr;`	U+02240	â‰€
`wreath;`	U+02240	â‰€
`Wscr;`	U+1D4B2	ð’²
`wscr;`	U+1D4CC	ð“Œ
`xcap;`	U+022C2	â‹‚
`xcirc;`	U+025EF	â—¯
`xcup;`	U+022C3	â‹ƒ
`xdtri;`	U+025BD	â–½
`Xfr;`	U+1D51B	ð”›
`xfr;`	U+1D535	ð”µ
`xhArr;`	U+027FA	âŸº
`xharr;`	U+027F7	âŸ·
`Xi;`	U+0039E	Îž
`xi;`	U+003BE	Î¾
`xlArr;`	U+027F8	âŸ¸
`xlarr;`	U+027F5	âŸµ
`xmap;`	U+027FC	âŸ¼
`xnis;`	U+022FB	â‹»
`xodot;`	U+02A00	â¨€
`Xopf;`	U+1D54F	ð•
`xopf;`	U+1D569	ð•©
`xoplus;`	U+02A01	â¨
`xotime;`	U+02A02	â¨‚
`xrArr;`	U+027F9	âŸ¹
`xrarr;`	U+027F6	âŸ¶
`Xscr;`	U+1D4B3	ð’³
`xscr;`	U+1D4CD	ð“
`xsqcup;`	U+02A06	â¨†
`xuplus;`	U+02A04	â¨„
`xutri;`	U+025B3	â–³
`xvee;`	U+022C1	â‹
`xwedge;`	U+022C0	â‹€
`Yacute;`	U+000DD	Ã
`yacute;`	U+000FD	Ã½
`YAcy;`	U+0042F	Ð¯
`yacy;`	U+0044F	Ñ
`Ycirc;`	U+00176	Å¶
`ycirc;`	U+00177	Å·
`Ycy;`	U+0042B	Ð«
`ycy;`	U+0044B	Ñ‹
`yen;`	U+000A5	Â¥
`Yfr;`	U+1D51C	ð”œ
`yfr;`	U+1D536	ð”¶
`YIcy;`	U+00407	Ð‡
`yicy;`	U+00457	Ñ—
`Yopf;`	U+1D550	ð•
`yopf;`	U+1D56A	ð•ª
`Yscr;`	U+1D4B4	ð’´
`yscr;`	U+1D4CE	ð“Ž
`YUcy;`	U+0042E	Ð®
`yucy;`	U+0044E	ÑŽ
`Yuml;`	U+00178	Å¸
`yuml;`	U+000FF	Ã¿
`Zacute;`	U+00179	Å¹
`zacute;`	U+0017A	Åº
`Zcaron;`	U+0017D	Å½
`zcaron;`	U+0017E	Å¾
`Zcy;`	U+00417	Ð—
`zcy;`	U+00437	Ð·
`Zdot;`	U+0017B	Å»
`zdot;`	U+0017C	Å¼
`zeetrf;`	U+02128	â„¨
`ZeroWidthSpace;`	U+0200B	â€‹
`Zeta;`	U+00396	Î–
`zeta;`	U+003B6	Î¶
`Zfr;`	U+02128	â„¨
`zfr;`	U+1D537	ð”·
`ZHcy;`	U+00416	Ð–
`zhcy;`	U+00436	Ð¶
`zigrarr;`	U+021DD	â‡
`Zopf;`	U+02124	â„¤
`zopf;`	U+1D56B	ð•«
`Zscr;`	U+1D4B5	ð’µ
`zscr;`	U+1D4CF	ð“
`zwj;`	U+0200D	â€
`zwnj;`	U+0200C	â€Œ

The glyphs displayed above are non-normative. Refer to the Unicode specifications for formal definitions of the characters listed above.

9 The XHTML syntax

This section only describes the rules for XML resources. Rules for text/html resources are discussed in the section above entitled "The HTML syntax".

The syntax for using HTML with XML, whether in XHTML documents or embedded in other XML documents, is defined in the XML and Namespaces in XML specifications. [XML] [XMLNS]

This specification does not define any syntax-level requirements beyond those defined for XML proper.

XML documents may contain a DOCTYPE if desired, but this is not required to conform to this specification. This specification does not define a public or system identifier, nor provide a format DTD.

According to the XML specification, XML processors are not guaranteed to process the external DTD subset referenced in the DOCTYPE. This means, for example, that using entity references for characters in XHTML documents is unsafe if they are defined in an external file (except for <, >, &, " and ').

10 Obsolete features

10.1 Obsolete but conforming features

Authors should not specify a border attribute on an img element. If the attribute is present, its value must be the string "0". CSS should be used instead.

Authors should not specify a language attribute on a script element. If the attribute is present, its value must be an ASCII case-insensitive match for the string "JavaScript" and either the type attribute must be omitted or its value must be an ASCII case-insensitive match for the string "text/javascript". The attribute should be entirely omitted instead (with the value "JavaScript", it has no effect), or replaced with use of the type attribute.

Authors should not specify the name attribute on a elements. If the attribute is present, its value must not be the empty string and must neither be equal to the value of any of the IDs in the element's home subtree other than the element's own ID, if any, nor be equal to the value of any of the other name attributes on a elements in the element's home subtree. If this attribute is present and the element has an ID, then the attribute's value must be equal to the element's ID. In earlier versions of the language, this attribute was intended as a way to specify possible targets for fragment identifiers in URLs. The id attribute should be used instead.

Authors should not, but may despite requirements to the contrary elsewhere in this specification, specify the maxlength and size attributes on input elements whose type attributes are in the Number state. One valid reason for using these attributes regardless is to help legacy user agents that do not support input elements with type="number" to still render the text field with a useful width.

10.2 Non-conforming features

Elements in the following list are entirely obsolete, and must not be used by authors:

The following attributes are obsolete (though the elements are still part of the language), and must not be used by authors:

The border attribute on the table element can be used to provide basic fallback styling for the purpose of making tables legible in browsing environments where CSS support is limited or absent, such as text-based browsers, WYSIWYG editors, and in situations where CSS support is disabled or the style sheet is lost. Only the empty string and the value "1" may be used as border values for this purpose. Other values are considered obsolete. To regulate the thickness of such borders, authors should instead use CSS.

The align, alt, archive, code, height, hspace, name, object, vspace, and width IDL attributes must reflect the respective content attributes of the same name. For the purposes of reflection, the


applet

element's object content attribute is defined as containing a URL.

The codeBase IDL attribute must reflect the codebase content attribute, which for the purposes of reflection is defined as containing a URL.

The behavior, direction, height, hspace, vspace, and width IDL attributes must reflect the respective content attributes of the same name.

The scrollAmount IDL attribute must reflect the scrollamount content attribute. The default value is 6.

The scrollDelay IDL attribute must reflect the scrolldelay content attribute. The default value is 85.

The cols and rows IDL attributes of the


frameset

element must reflect the respective content attributes of the same name.

The name, scrolling, and src IDL attributes of the


frame

element must reflect the respective content attributes of the same name.

The frameBorder IDL attribute of the


frame

element must reflect the element's frameborder content attribute.

The longDesc IDL attribute of the


frame

element must reflect the element's longdesc content attribute, which for the purposes of reflection is defined as containing a URL.

The noResize IDL attribute of the


frame

element must reflect the element's noresize content attribute.

The marginHeight IDL attribute of the


frame

element must reflect the element's marginheight content attribute.

The marginWidth IDL attribute of the


frame

element must reflect the element's marginwidth content attribute.

The coords, charset, name, rev, and shape IDL attributes of the a element must reflect the respective content attributes of the same name.

The noHref IDL attribute of the area element must reflect the element's nohref content attribute.

The color, face, and size IDL attributes of the basefont element must reflect the respective content attributes of the same name.

The text IDL attribute of the body element must reflect the element's text content attribute.

The link IDL attribute of the body element must reflect the element's link content attribute.

The aLink IDL attribute of the body element must reflect the element's alink content attribute.

The vLink IDL attribute of the body element must reflect the element's vlink content attribute.

The bgColor IDL attribute of the body element must reflect the element's bgcolor content attribute.

The background IDL attribute of the body element must reflect the element's background content attribute. (The background content is not defined to contain a URL, despite rules regarding its handling in the rendering section above.)

The clear IDL attribute of the br element must reflect the content attribute of the same name.

The align IDL attribute of the caption element must reflect the content attribute of the same name.

The align and width IDL attributes of the col element must reflect the respective content attributes of the same name.

The ch IDL attribute of the col element must reflect the element's char content attribute.

The chOff IDL attribute of the col element must reflect the element's charoff content attribute.

The vAlign IDL attribute of the col element must reflect the element's valign content attribute.

The compact IDL attribute of the dir element must reflect the content attribute of the same name.

The align IDL attribute of the div element must reflect the content attribute of the same name.

The compact IDL attribute of the dl element must reflect the content attribute of the same name.

The name and align IDL attributes of the embed element must reflect the respective content attributes of the same name.

The color, face, and size IDL attributes of the font element must reflect the respective content attributes of the same name.

The align IDL attribute of the h1â€“h6 elements must reflect the content attribute of the same name.

The align, color, size, and width IDL attributes of the hr element must reflect the respective content attributes of the same name.

The noShade IDL attribute of the hr element must reflect the element's noshade content attribute.

The version IDL attribute of the html element must reflect the content attribute of the same name.

The align and scrolling IDL attributes of the iframe element must reflect the respective content attributes of the same name.

The frameBorder IDL attribute of the iframe element must reflect the element's frameborder content attribute.

The longDesc IDL attribute of the iframe element must reflect the element's longdesc content attribute, which for the purposes of reflection is defined as containing a URL.

The marginHeight IDL attribute of the iframe element must reflect the element's marginheight content attribute.

The marginWidth IDL attribute of the iframe element must reflect the element's marginwidth content attribute.

The name, align, border, hspace, and vspace IDL attributes of the img element must reflect the respective content attributes of the same name.

The longDesc IDL attribute of the img element must reflect the element's longdesc content attribute, which for the purposes of reflection is defined as containing a URL.

The align IDL attribute of the input element must reflect the content attribute of the same name.

The useMap IDL attribute of the input element must reflect the element's usemap content attribute.

The align IDL attribute of the legend element must reflect the content attribute of the same name.

The type IDL attribute of the li element must reflect the content attribute of the same name.

The charset, rev, and target IDL attributes of the link element must reflect the respective content attributes of the same name.

The compact IDL attribute of the menu element must reflect the content attribute of the same name.

The scheme IDL attribute of the meta element must reflect the content attribute of the same name.

The align, archive, border, code, declare, hspace, standby, and vspace IDL attributes of the object element must reflect the respective content attributes of the same name.

The codeBase IDL attribute of the object element must reflect the element's codebase content attribute, which for the purposes of reflection is defined as containing a URL.

The codeType IDL attribute of the object element must reflect the element's codetype content attribute.

The compact IDL attribute of the ol element must reflect the content attribute of the same name.

The align IDL attribute of the p element must reflect the content attribute of the same name.

The type IDL attribute of the param element must reflect the content attribute of the same name.

The valueType IDL attribute of the param element must reflect the element's valuetype content attribute.

The width IDL attribute of the pre element must reflect the content attribute of the same name.

The align, frame, summary, rules, and width, IDL attributes of the table element must reflect the respective content attributes of the same name.

The bgColor IDL attribute of the table element must reflect the element's bgcolor content attribute.

The cellPadding IDL attribute of the table element must reflect the element's cellpadding content attribute.

The cellSpacing IDL attribute of the table element must reflect the element's cellspacing content attribute.

The align IDL attribute of the tbody, thead, and tfoot elements must reflect the content attribute of the same name.

The ch IDL attribute of the tbody, thead, and tfoot elements must reflect the elements' char content attributes.

The chOff IDL attribute of the tbody, thead, and tfoot elements must reflect the elements' charoff content attributes.

The vAlign IDL attribute of the tbody, thead, and tfoot element must reflect the elements' valign content attributes.

The abbr, align, axis, height, and width IDL attributes of the td and th elements must reflect the respective content attributes of the same name.

The ch IDL attribute of the td and th elements must reflect the elements' char content attributes.

The chOff IDL attribute of the td and th elements must reflect the elements' charoff content attributes.

The noWrap IDL attribute of the td and th elements must reflect the elements' nowrap content attributes.

The vAlign IDL attribute of the td and th element must reflect the elements' valign content attributes.

The bgColor IDL attribute of the td and th elements must reflect the elements' bgcolor content attributes.

The align IDL attribute of the tr element must reflect the content attribute of the same name.

The ch IDL attribute of the tr element must reflect the element's char content attribute.

The chOff IDL attribute of the tr element must reflect the element's charoff content attribute.

The vAlign IDL attribute of the tr element must reflect the element's valign content attribute.

The bgColor IDL attribute of the tr element must reflect the element's bgcolor content attribute.

The compact and type IDL attributes of the ul element must reflect the respective content attributes of the same name.

The attributes of the Document object listed in the first column of the following table must reflect the content attribute on the body element with the name given in the corresponding cell in the second column on the same row, if the body element is a body element (as opposed to a


frameset

element). When there is no body element or if it is a


frameset

element, the attributes must instead return the empty string on getting and do nothing on setting.

11 IANA considerations

11.1 text/html